Charging twice for the same landline

Last year, I transfered my boyfriend's account into my name. The landline number did not change, and I received the Telkom bills in my name. We are now finding out that the old account in my boyfriends' name is still running and has been charging us every month. How is it possible that Telkom forgets to cancel the account? They told us : "pay the last bill in the old account and then it will be it, it is canceled by the new account anyway". Instead they kept charging. So instead of paying one bill, we've been paying two, for the same landline! We ended up being disconnected, then paid a reconnecting fee, without understanding why we're paying so much money every month and still owing. We've been trying to sort out this mess but no one is able to explain anything.