i am billed for a sim card which is not working

I had a problem with my employer and was not paid for three months thus my debit orders including mtn *** were not going through. After getting paid i immediately cleared all my debts including mtn. They informed me tht the case was now with their legal department. I try to call this so called legal department and no one responds. Since september i am billed by mtn for a contract line which is not working eventhough i dont owe them a cent upto date. They can contact me on *** which is a vodacom number since they have cut off my sim card for mtn. My email adress is [Email Removed] Am looking forward for your much needed assistance