Bad service tekkie town

I had a really bad experience at Evaton mall tekkie town. I was interested in buying a Nike sneaker at their store. The shoe had a tag price of R899 and 30 percent off. When I went to the till in order to pay, it was brought to my attention that the shoe I'm interested in is the last pair, but on the box it was a different price and no longer R899 as shown in the tag. Instead it was now R1,200. When I asked why aren't the prices the same because as a customer I should pay the price I've seen? I was instead given bad treatment and no valid answer as they made a runaround. I decided to leave as I can't stand such bad service. It's really unacceptable. According to consumer rights I pay for the price I've seen!