Nightmare to cancel my account

I have been a prestige client who buys a little and pays it off. I originally opened this account to build up my credit score and now I am apparently not able to cancel it.

I went into the shop at Mall of Africa on 07/01/2020 to pay off and close my account. The gentleman assisted me and said all was processed. He gave me proof of payment and proof of the fax he sent off to his head office. In April I get a call from a call center agent wanting to talk about my account to which we discussed again it should have been cancelled and I sent her the proof. NOW yesterday the 22/06/2020 I get a call from someone in the accounts department who tells me my account is in arrears and I completely lost it. I asked for a manager and she couldn't let me speak to one so I asked for a managers email address to which she provided me with ***. I have sent 2 emails and no response and now I receive an sms telling me my account has blocked.

Either you sort this out before it effects my ITC report or I will take this further.

I look forward to finally getting some sort of response.