Extremely disappointed at Pep clothing Tambotie Mall

I'd just like to express the shock and disappointment at thr treatment I received at Pep clothing at Tambotie mall today. I went there, bought 2 jeans for my girls. The price tag on thr jeans was R79,99 right. So I went to the tills, payed and left. When I got home I went through the slip and realized the price on the slip says R89,99. So I drove back to PEP to enquire about this, I told the lady at the door by the name of Livhhwani what had happened and she said the cashier probably didn't see it. She told me to go to the tills and I did exactly that. I was assisted by the same lady who assisted me earlier, her name is Sinazo. So I show her the slip and the price on the jeans. So she says "ooh, it did that again". Then she asks me to complete my details on the back of the slip, I did that. I then explained to her I'm not returning the jeans but I just want you to fix the error. Then she goes ahead and loads a refund, then she calls Livhuwani to come and override. Then theg give me my money back, then I ask what's going on? Sinazo explained to Livhuwani that we are not returning the jeans, the price tag says R79, 99 but when she scans them it says R89, 99 so they must fix it. Then Livhuwani says to me if I want those jeans I must buy them for R89, 99.she says they have already done a refund so I must buy them for R89, 99, I then ask why must I pay a different price to what is on the price tag. I'm shocked really, why must I pay R89, 99 when the price tag says R79, 99? Is this even allowed? Is this how PEP conducts business?