Im Stuck with MTN

I had an account with MTN i paid it up last month in full, i received and email from their legal team confirm the account is now closed. Im busy applying for a home loan but that MTN account is still appearing under my name is unpaid and in default, i called mtn but their customer care number is pathetic as they want a cell number- i had a laptop with them, i emailed them again 2 days again i need a paid up letter or for them to go on transunion to update my record please and still no feedback.