Requesting a Settlement letter

I've been dealing with this issue the entire year with no resolution.

My telkom account was handed over to a company named NuDebt with an outstanding balance of R2400+ which i disputed with them and sent them all the relevant documentation. When they dispute was finalised NuDebt sent me a confirmation email saying that my balance is R897.00 and i made an arrangement to settle the amount by month end. But what they did or Telkom did they gave/sold my account to another company called Debt-In which tell me that i'm owing them and amount of R3400+, they swear at me on a daily basis, they are very rude they don't want to escalate nothing to telkom or nudebt they keep telling me i'm dealing with them and that is that.

I've paid the settlement amount with telkom and i'm looking for a settlement letter and my credit record to be adjusted immediately as i don't have time to deal with Debt-In or Telkom.

Please Telkom assist me before i loose my mind with these phone calls that come at any time of the day.

I want to stop dealing with you as soon as possible, please please please do that for me.