Prescription letter for an account

It’s been 3 months now trying to get a prescription letter from MTN ,as my name cannot be removed from debt review due to them ,they say they can’t find my account number as it is on the old system meaning they can’t help me ,they can’t give me any form of letter mind you without this letter I’ll forever be under debt review I’ve emailed them more than 50 times giving them my ID number giving them the account number that I have that was given by them to the debt review company 10 years ago when I had app**** to @debtrescue, the company itself also emailed MTN and they have failed to reply to them when I call MTN I’m being asked questions like are you sure you even had an account with MTN please send more proof, Iv emailed all necessary departments and none of them to date has gotten back to me with a better answer besides we cannot find your ID or account number,all I’m asking for is a prescription letter for this account or a letter that states that my account cannot be found due to the system change as it’s not my fault that systems have changed and old accounts were not brought to the new system