Being threatened after settling account

I am writing this on behalf of my father. In March this year he went to the promenade store In Mitchells' Plain where he then settled his account. The consultant at the store then called Customer Service to close the account. My father then spoke to customer service who advised him that the account has now been closed and that he will receive a paid up letter- something which he is still waiting for. One month down the line he receives staterments stating that he still owes more than R500.00 on his account which has now accumulated to the point where he gets sent sms'es on a daily basis for non payment and that he will be blacklisted if R100.00 is not being paid on the account. My father then went to the store on numerous occasions where he was told that he made a purchase of R150.00 which now accrued over time but the funny thing is that this account has been closed. He was then also told by the store manager that they unable to assist him regarding this matter. Please assist as he is considering going to the retail ombudsman regarding tis issue. Father's name: Brindley Aurin Keur