BAD SERVICE MORE THAN ONCE THEN CREDIT DISAPPEARS MORE THAN ONCE!!!!!

Firstly I pay my account every single month on time. So whenever I buy things and it doesn't fit and I return it back to the store I noticed that My credit is never right compare to what is was before I even bought the items.... So on Friday 10/11/2017 I bought a few items at jet in Parow Centre which came to R235.96 and after that it showed that I still had R162.04 credit available. So on Monday 13/11/2017 I went to Edgars to purchase a slim fitted shirt for my fiancée and the guy at the teller told me that my account is over sold I couldn't believe it as I know I had credit still and I did not make another purchase after Friday. He then called their customer services and how rude they didn't even want to speak to me as a customer but rather told him to explain to me that I am not the first customer that complained about it after making purchase on Friday and that it is a system problem... Okay I let it go. So today I go back to Jet and a Lady by the name of Melissa Kwalie checked again and said but my account is still over sold and that there is nothing they can see or do at store level and that I should call customer service again which I already did and yet still no results because my account credit was still gone.... Whenever I come into that Jet or Edgars store in Parow centre you always have to stand 10 years in a line because there are always just 1 or 2 cashiers or they just busy doing there own thing.... I am so fed up with Edgars and there bad service and my credit disappearing..... If nothing gets done after this I WILL TAKE IT FURTHER!