Misleading price

On 21 December 2017 I bought a cell phone from pepstores queens mall in oudtshoorn. When i look at the display cabinet the price was 799, but when i got to the till it was a total different price, the phone then cost me R999.00 < When i asked the cashier the cashier but why a different price now, she told me she dont know, then she called the manager then informed me that that phone cost R799 was out of stock, i told her i thought i was purchasing a R799 cell phone she said no its out of stock.... Excuse me what happend to what the customer shes the customer pays for! I then left the store very unhappy with the phone that cost me r999