Worst service

Went to shell deli to buy something to eat and drink. Saw they have a special on a pie, coke and chocolate for r40. On the special paper it shows 440/500ml. So i took the 500ml glass bottle as the special didn't specify a nrb or anything. At the till i saw the price wasn't the specail price. I said to the cashier why isn't it the special price. She said it must be the plastic bottle. I told het it showed 500ml bottle as the special said nothing that it must be coke light or coke zero. With the rudest attitude and screaming at me she said "this is not the special and not gona give you this bottle." I asked for the manager. Also the rudest attitude she said it must be the plastic bottle. I tod her it shows 500ml. Nothing that it must be a nrb or coke lite or coke zero.... she said its not her problem and walked away. The cashier said to the manager some customers have **** attitudes. Im disgusted with the way customers are treated in this shop. And they must specify the specials... name of cashier, patience Name of manager, penny