McDonald's

Today was my son's 1st day of school. I decided to treat him to lunch at McDonald's to make his day complete. I pulled up to the drive thru and ordered a 6 piece chicken nuggets, medium fry and a hamburger happy meal with a fruitopia. I was given a bag with french fries in it and a few minutes later was handed the happy meal. I started to look through the bag to see where the hamburger was and heard the drive thru attendant say loudly "wha'ts she still sitting here for?" I wasn't asked if everything was okay. I told them that I was waiting for a hamburger and was told to check my receipt. I was then rudely told that it was in the happy meal box. Why it was in the box with food after it touched many hands, is beyond my understanding. Why the attendant couldn't have checked her screen to make sure my order was complete was also beyond me. I read the receipt told them the burger was missing and was given one with a hasty I'm sorry. Not one of my best customer service experiences