UNISA Account Issues with no reponse

Not sure what is going on within UNISA with Covid-19 etc but I have not been able to get any response since last year about an outstanding payment on my account, which has been paid with proof sent, and yet nothing but repeated statements with the outstanding payment. I went to query this at one of the accounts department which landed up not being open due to COVID so I'm stuck phoning and emailing. I've phoned many times sitting on the line for hours (not an exaggeration) and that is when the lines are actually working. I only once got through to someone who just redirected me to the accounts complaint email that I already used from the main website. I've received multiple auto responses and reference numbers but no actual call back or human acknowledgment. I'm patient but refuse to pay double to stay registered in the hope that their account department will acknowledge their error and refund me. It has been two semesters that have passed since I started this process and if this is not sorted soon I'll need to reregister next year because of it. I'm hoping UNISA picks this up and gets back to me or else I'm out of options.