When you work for a salary and not to please patrons

I stopped at BP South Drive thru on the way from Pretoria to buy supper for my family and upon receipt of my meals, I specifically asked the guy at the window if all meals are checked and in the bags, he confirmed it had been. Got home and found a Big Mac burger short. I tried calling on ***, but no answer. It appears that McDonalds franchises are losing their sense of service. It’s frustrating having asked and still find something missing. I am livid as I live far from the ****** restaurant.