Poor Communication

I have paid up my Credit card with African Bank on the 23 of May and I told them I want my account closed. The week after I still receiving phone calls that my account is arrears, I told them I have settled my account and my account is closed. They still harassing me with phone calls 4/5 times a day after I have sent them many emails with the proof of payment that I have paid the settlement and I want my account closes. One message I receive told me its been resolved and the next phone call the tell me again I must make payment my account is arrears.. it is absolutely ****** ridiculous.. Today on the 10 of June I spoke again to one of African bank's consultants and again I have sent the proof of payment. Not even half an hour later another consultant phone again.. telling me I must make payment... Beyond ridiculous