keep being transfered from one person to another

i had an account with mtn in 2012,i settled the account an paid it off,they i realized it was not closed when i check my credit report,i called in spoke to some guy who said it was not a problem as the balance is 0 an it should be closed off,i checked an realized it is still open,i have called mtn i dnt know how many times they keep telling me the account is with legal an they keep transferring from one person to another an telling me legal does not answer calls,how am i supposed to get help if they not answering calls ,i have been on a call for 3 hours today an im still being transferred,no one knows how to help me .