YDE - harrasment to pay an already closed account

I opened a YDE account the first week in June 2015 and made purchases on the day the account was open. <br> <br> Three weeks later, 29 June 2015 (BEFORE the first installment was even due) I settled the account in full at Kolonade branch and closed my account. <br> <br> Yet I still received sms's asking for payment - I called the given number numerous times and they only said that they cant assist me, I should call their head office (why give the number if you cant even assist). <br> <br> Now, three months later they have handed the account over to MDCS who have also sent numerous thretening correspondense. We have spoken to three consultants and sent proof of payment to three different emails, and yet they dont update their records - they just keep sending demanding letters day after day. <br> <br> This is really rediculous! Can someone please just do something about this??? Its very time consuming and frustrating to deal with this!!!