I'm a police officer!!

So this family comes in and you can just tell they are going to moan!! They order four meals and four drinks. We use the buzzers and they have to come to the bar to collect their food. They came got their food and sat back down. About 10 mins later this "Karen" comes storming up saying that her curry is cold and horrible and wants a refund now! I said I'm sorry about this if you want to bring your plate back I will refund you. She went to get her plate and then said she wants a refund for everyone else as their food was horrible too. (The other three people she was with ) I asked her to bring all the plates back to me. She then took a bit of time to come back with the other plates, She placed the EMPTY PLATES on my counter! I said I can't give you a refund for the three empty plates but I will do for her one she was unhappy about. Then she started shouting at me saying I need to refund her for all four meals! My manager was behind me and heard everything. My manger explained that the empty plates have been eaten so we will refund for the one meal. Then the "Karen" started telling my manager that she was a police office and she needs to do what she says!!! My manager said that it doesn't matter if she's a police office she's only getting a refund for the one meal! Her friend then came up to apologise to us and excepted the refund. They all left as I think they other people was embarrassed with this woman. As she left she shouted she was going to come back and arrest us!!! ha ha we are still waiting for the police!!