UberEats and McDonalds Silverton con scheme!!!

Went to McDonalds Silverton today. Was helped by Uber Eats guy to order via app as I was unable to log in. I ordered 12 BigMac Meals, 4x 6 piece nuggets and 1 Oreo McFlurry. He said the total was R1330 and without pre calculating the total, a friend of mine paid that amount as I was not with at the time. Before leaving the parking, I check amount of meals and they were correct. I asked for a slip and the Uber Eats guy apparently "lost it" . When I reached home, I re-calculated the total and found out that I was overcharged. Unfortunately couldn't go back to McDs as it is quite a distance from my house and conveniently, I had no proof of this order seeing that I did not get a slip. This is a con scheme and I refuse to take it lightly. I will email and call for the manager of this outlet until I get an answer..