Well, it has happened to me a couple of times. But take an example. I bought a PS2 dock which costed 1546 QR. but in the bill they charged me 2546 QR. I went back to the customer service and told them the case, they didn't know what to do, so they called the cashier who made the transaction and the manager. When the manager saw the bill and the price of the product, he told the cashier to return all the money back to me including the original 1546 QR. I got my dock for free!!! That's the joy. Don't be afraid of them dude. They have to run their business in every illegal way they can.