Unsatisfactory service provides

I bought pumps on promotion at kerk street Woolworths but only wore it for 1 and a half month so I went back to return the shoes cause clearly it was evident that it was a quality issue, the lady who assisted me asked if I'd paid with my woolliescard and I said yes so she went to check and came back saying i' d paid 82.50 and I told her no it was around 90 something rands of which she was totally disagreeing with me. The manager or supervisor asked her if she'd not checked the amount and she said she will go and double check so she went and that took forever she came back still claiming I'd paid 82.50 the manager asked if I'm satisfied I said no and she refunded 85. I left as i was running out of time so I went back to work and I recalculated and figured I'd been ****** of 7.50 so I phoned the store and spoke to Precious who confirmed I was refunded less and she said I should come back and ask for her or the other manager and upon my return to the store I was told to wait as they call for Precious and that took forever until Bridgette was called to assist as Precious had left already at 3pm. What an inconvenience yet again and what's worse is Bridgette offered to attend to my query and now again I must explain myself only for her to tell me the difference owed to me is supposed to be overrided by Precious and I asked for the store manager and got told the store manager was also not available. Is this how a customer is supposed to be treated and the run around for a human error that could have been prevented had the assistant listened to me and not do things according to her understanding just because I received discounts on the shoes. I want my refund done but I'm sorry the managers will have to find a way to return the funds to my store card as I've lost time from work and money travelling to and from the store for nothing