Best to pass a situation like that on to a manager if you can.

I think I would be tempted to just validate any coupons from now on. That way you don't get complaints, which are the black marks, and hopefully no one notices the date on the coupon. (This only works on my assumption that no one goes and checks all the coupons or something, and that you are the last stop for them). I'd also tell the manager how unfair it is you're getting black marked for doing your job properly and ask for a policy change. I don't know if you're unionized or have HR or someone higher to go to, but I'd really be trying for a policy change seeing as it's stupid and I bet every employer would also want the change. Policy should be changed to complaints only giving a black mark if there's proof or reasonable grounds to the complaint.

Yeah, but it's still a complaint on *your* record. It can be waved off if it's a complaint in person, but if it's filled out online, you're fucked, because it's straight to regional/district manager.

Agreed! I had a table of loud mouthed twits, when one of them accidentally took the others meal the woman lost her shit at me, I politely explained what happened and told her i would get my manager..... Apparently she lost her shit on my manager about what a rude bitch I was and how I blamed it all on them. Manager and I had a good bitch session about how horrible she was but I still had to be given a "verbal warning" because of the complaint

If he had honored it then his boss would have complained and put it on his record anyway.