*****ing from customers!

Last night I placed an order at the McDonald's drive-through in Karen Park Pretoria. I bought 3 Big Mac medium meals as well as 3 Caramel dip cones. Unless my calculations are wrong, if a Big Mac meal is R42 each then that comes up to R126. Adding the the dipped cones which are R9. 90 each, the total price should have come to the region of R155 give or take. The price given to me at the order point of the drive-through was R153. When I got to the paypoint I was charged R172. I queried this as it didn't make sense for me to get 2 different prices and I was dismissed by another staff member with the flimsy excuse that the previous price only app**** if I had purchased coke instead of coke light with our meal. Please find attached my slip which doesn't even describe my exact order. Is this how the employees **** us out of our money? Do they think we all just drive off without checking our slips? I'm so angry and disappointed that they couldn't even admit their mistake. This is a branch we have supported for many years including hosting parties there and this is how we are treated?