Waiting 6 months for a written off letter

My husband has an account of five years ago that has been written off and he has been told by the lady that assisted him that she would send him a written of letter via email that was in April 2019 since then we have been calling every week cause no email has been sent. He then spoke to another person and she said it was written off but there's a percentage he has to pay in order for his credit score it go up we don't mind paying a percentage we just need a letter so his name can be cleared but no one ever gets back to us. Sometimes we are left on hold for more than 30 minutes last week we called and asked to speak to a manager but when they put him through he was left on hold for 15 minutes then got cut off! I have got about 5 different email addresses that I received from the employee's cause they say we have to send a email requesting a paid up letter but none of them exists.