Two stories for you guys today! 
First one was told to me by a coworker. (I work in an entertainment store, for the record. Movies, books, games, music.)
He's checking people out at a register, and two young-ish (about 8 and 14) kids come up with a rental movie, and their mother's ID. Coworker looks up the rental account using the ID and the following ensues.
CW - coworker
K - Kid(s)
M - Mother
CW - (seeing that the movie is rated R and that the kids are not listed as okay to rent to on the account) Sorry guys, I can't let you rent this.
K - Why not??
CW - Your mother needs to be here, I'm sorry.
Kids leave, come back in with the mother, who's PISSED OFF.
M - WHY CAN'T MY KIDS RENT THEIR MOVIE!?
CW - I'm sorry ma'am, but they're not listed on the account as secondaries and to be honest, the movie they were trying to rent is rated R. I can't rent to them without you being present and okaying it.
M - That's bull%^*$, how do you think they had my ID?
CW - I have no way to be sure of that ma'am, but you still needed to be present either way.
M - That's stupid, who do you think you are telling my kids they can't rent something when I told them it's okay?!
CW - One of the managers here.
M - You just won't rent to them, because it's discretion!!
CW - ... Do you mean discrimination?
M - Whatever!! We're keeping our money!!! *leaves*
CW -
And this lovely one was a joy for me to handle today...
Me -
L - Lady on phone.
(Little bit of background.. yesterday our debit/credit card system went down and would time out trying to process, so we had a bit of trouble for a couple hours.)
Me - (greeting) how may I direct your call?
L - I was in there yesterday and the lady told me there that the debit machine was down (that was me :P) and we tried it anyway and it didn't go through on mine or my daughter's card so we paid cash. And now we look and I have two charges from you guys on my card and one on hers for all the same amounts, even though we paid cash!!
Me - Okay, I'm so sorry about that, we were having difficulty with the system then. If you just bring in both your banks' statements we'll get that refunded for you no problem.
L - ... You don't get it. We were charged on our cards even though we were told it didn't go through and it did!
Me - I understand that, and I apologize for it, our system had said it didn't go through. It'll be easy to fix though, just go ahead and bring in your statements and we'll refund it.
L - But... no... wait. Don't you have it there?
Me -
Have what here, I'm sorry...?
L - That we were charged.
Me - N-no... the register stated that it didn't process, and no receipt was printed. We had no way of knowing that it had charged you.
L - You should have record of it charging me there!!!!
Me - No ma'am, we don't. It'll be easy enough to fix though, we just need your statements -
L - You're not understanding me. We were charged... ugh...
Me - I understand perfectly ma'am. All you need to do is bring in your bank statements. We don't have anything here that says you were charged. With your statements as proof, it won't be a problem to refund it. *starts to feel like a broken record*
L - I .. well.. but.. UGH. Fine. We'll print it out. And be there. Thank. You. *hangs up*
Me - *sigh of relief* (to customer at register) Sorry about that.
Customer -
No problem, I understood you the first time you explained it myself, hehe.

First one was told to me by a coworker. (I work in an entertainment store, for the record. Movies, books, games, music.)
He's checking people out at a register, and two young-ish (about 8 and 14) kids come up with a rental movie, and their mother's ID. Coworker looks up the rental account using the ID and the following ensues.
CW - coworker
K - Kid(s)
M - Mother
CW - (seeing that the movie is rated R and that the kids are not listed as okay to rent to on the account) Sorry guys, I can't let you rent this.
K - Why not??
CW - Your mother needs to be here, I'm sorry.
Kids leave, come back in with the mother, who's PISSED OFF.
M - WHY CAN'T MY KIDS RENT THEIR MOVIE!?
CW - I'm sorry ma'am, but they're not listed on the account as secondaries and to be honest, the movie they were trying to rent is rated R. I can't rent to them without you being present and okaying it.
M - That's bull%^*$, how do you think they had my ID?
CW - I have no way to be sure of that ma'am, but you still needed to be present either way.
M - That's stupid, who do you think you are telling my kids they can't rent something when I told them it's okay?!
CW - One of the managers here.

M - You just won't rent to them, because it's discretion!!
CW - ... Do you mean discrimination?
M - Whatever!! We're keeping our money!!! *leaves*
CW -

And this lovely one was a joy for me to handle today...
Me -

L - Lady on phone.
(Little bit of background.. yesterday our debit/credit card system went down and would time out trying to process, so we had a bit of trouble for a couple hours.)
Me - (greeting) how may I direct your call?
L - I was in there yesterday and the lady told me there that the debit machine was down (that was me :P) and we tried it anyway and it didn't go through on mine or my daughter's card so we paid cash. And now we look and I have two charges from you guys on my card and one on hers for all the same amounts, even though we paid cash!!
Me - Okay, I'm so sorry about that, we were having difficulty with the system then. If you just bring in both your banks' statements we'll get that refunded for you no problem.
L - ... You don't get it. We were charged on our cards even though we were told it didn't go through and it did!
Me - I understand that, and I apologize for it, our system had said it didn't go through. It'll be easy to fix though, just go ahead and bring in your statements and we'll refund it.
L - But... no... wait. Don't you have it there?
Me -

L - That we were charged.
Me - N-no... the register stated that it didn't process, and no receipt was printed. We had no way of knowing that it had charged you.
L - You should have record of it charging me there!!!!
Me - No ma'am, we don't. It'll be easy enough to fix though, we just need your statements -
L - You're not understanding me. We were charged... ugh...
Me - I understand perfectly ma'am. All you need to do is bring in your bank statements. We don't have anything here that says you were charged. With your statements as proof, it won't be a problem to refund it. *starts to feel like a broken record*
L - I .. well.. but.. UGH. Fine. We'll print it out. And be there. Thank. You. *hangs up*
Me - *sigh of relief* (to customer at register) Sorry about that.

Customer -

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