No good deed goes unpunished

I am a regular customer at the Pick and Pay Hypermarket in Port Elizabeth (William Moffet). I happened to notice that the file dividers were priced incorrectly (grossly under-priced) and I mentioned this at the till. Initially, the cashier indicated that the scanned price is what you pay. However, knowing that the price was way below what I should pay, I agreed that the manager should be called. The cashier assistant went to the manager (Shaun) and returned (after a long while) without the said manager. The packet of file dividers was now open and she indicated that I have to pay R10 each. I did not mind paying the correct price, however I feel the manager should of come to me personally (especially after such a long wait) and apologize for their error. He however, decided to ignore the situation.