Account settled years ago

I have had an account with MTN years ago, which was settled and proof that it was settled has been sent from my mother on behalf of me round about 2007. When I wanted to try and apply for a top-up account one of your very friendly (not sarcastic) store consultants advised me that my account is still with the legal department and has never been released. How can you not release accounts that has been settled even with proof that was sent. Unfortunately I do no longer have that proof as I have thought that this was dealt with whilst I was overseas. Please can we find a way to rectify this issue?