Burger King complaint

I was treated very poorly by the cashier. I've been a loyal customrer to this Burger King location and that was by far and away the worst experience I have ever had. She would not accept my Burger King coupon for a free sandwhich and made up a lie that said that it expired on November 30th. There is no place on the coupon where it says it has an expiration date and the week before I used one just like it and it was accepted at this same restaurant. Futhermore she did not look at me when she said thank you she just handed me my bag of food and looked at the french fry holding machine instead. I still have my receipt and hope the manager can find out who waited on me today.