Mtn south Africa

Good morning I had account with mtn 2*** I lost my job recently I found job .I'm working now I called mtn because I want to settle my account it was difficult I even we t to mtn branches no luck bcz they keep saying it's old account they don't see me but last week Tuesday they said I must pay 3998.18cent I paid 4000 it's been weeks days I send email to their legal team no response what can I do in situations like this I don't get any help the only thing I need from them is proof that my account has been paid