Price fixing, unexplained to customers

Reason for this rating is due to disappointment how the drive thru operates, not honest. I ordered a meal for R69.00 and at the collection window I got a receipt with a charge of R73.00 and asked why the price difference. Their answer was " sir you changed your drink from diet to regular Pepsi, while my order was a meal with its original drink on the menu... They refused to refund and didn't get the drink. I just didn't have time for their nonsense, I left cause I really was hungry but I'm not going back to that branch period.