Cell C store East Rand mall

I visited the Cell C store at East Rand Mall in Boksburg to purchase a car charger. The price on the Snug charger was R399. When it was time to pay, I was asked to pay R499. I told them that it's my right to pay the displayed price and their excuse was simply that they are awaiting the guys that change the display prices. How is that my problem. I bought the same charger, a hundred meters arounf the corner from them at the Vodacom shop for R399. Disgusted by the service.