I was charged for a large meal only to get a regular meal 😡😡😡😡

I am not happy with the service I got at McDonald's Diepkloof square, I brought a large BIG MAG only to get home and find that they gave me a regular meal, went back only for them to tell me that only the fries and cold drink are large not the burger, what I don't understand is why did they charge me for large everything yet I'm only gonna get fries and cold drink large.... I'm no fool and right now I'm ****en ****ED 😡😡😡😡 I don't think I'll ever buy at McDonald's