2 of us in our party were double charged for drink...

2 of us in our party were double charged for drinks. We paid cash the first time and were not offered a receipt. Then we ordered food and were charged again for the drink with the food. I confronted the bartender and he said I was wrong. I showed him the change from the drink and he tried to tell me I ordered 2. He was padding the bill. No manager on duty. Won't ever go back. This guy needs to be fired.