Bad customer service MR PRICE SHOP NUMBER 210-212 CHURCH STREET PIETERMARITZBURG

I had placed an order online and some of the clothes I had purchased did not fit me so I tried exchanging them at MR PRICE SHOP NUMBER 210-212 CHURCH STREET PIETERMARITZBURG on Monday the 4th of April, I was not able to get the assistance I required, at first the lady cashier who tried processing the clothes said that I needed to pay an extra R580 which did not make sense to me as the clothes I was returning amounted to the same amount of the one's I was returning so when I told her I don't understand what she was saying she called another gentleman which I unfortunately did not get his name (but he was coloured) who seemed to at least know what he was doing, when he continued processing the exchange it turned out I was only owing an extra R11 not R580 as the other lady was insinuating but unfortunately when it was time for me to pay the difference the system showed an error message and as a result they were not able to assist me. The gentleman tried calling mrp online support to no avail, they took down my details and promised to get back to me the following day of which they haven't called me and now I am stuck with these clothes not sure how to proceed as I don't wish to go and stand in their long queue without assurance that I will be assisted, maybe the staff should receive training on how to process online returns or how to deal with online orders since customers are expected to do returns in store.