Incorrect order And Bad service

I have just gone through the drive through at McDonald’s Pinetown and ordered a burger meal for my son. I asked for no sauce no garnish and it was a R39,90 meal, and Mbanjwa asks me what drink I want I tell him Fanta orange when he rings the order it comes up to more than 39,90 and he tells me it’s because it’s a bigger drink and I tell him I don’t want a bigger drink, he says then you can only have Sprite not Fanta so I just accept. I get to collection I take my order and then I ask my son to check the order before we left and unfortunately He didn’t check properly and he thought it was fine but he actually opened the side that has nothing. When we get home he takes a bit and as soon as he starts chewing it has sauce and garnish and immediately he had rash and a swollen mouth because he doesn’t eat these ingredients. I can’t turn back and I’m more than 15km from McDonald’s.