Very Disgusted in the service

I'm so disgusted in jet n1 city. I will never go shop there again. I received a baby outfit as a gift but was to small so I had to change it for a bigger size. When i went there they didn't have the outfit in stock then I chose a different out and was going to pay the outstanding balance, but when I went to pay the outfit that I wanted to changed was marked down but had no sticker on it to say it was marked down. Basically the outfit I was exchanging was R60 and suddenly was marked down to R20 so that means I lost R40. They cannot do it when I asked the manager or supervisor but where is the sticker she said its what the computer says. The are so unprofessional. I want this matter resolved because if not I will be taking this even further as this is day light *******.