MTN does not even deserve 1 star, its too high for them

MTN does not even deserve 1 star, 1 star is even to much for MTN. After numerous conversations with their stores and customer care center's, after following all their instruction on ending our contract to be migrated to pay-as-you-go, on the dates that they said it should be done we still get an invoice to pay the amount of the invoice. After confirmed mistakes from MTN side as they self do not understand what is going on on the account, we are being threatened with legal action and our lines being switched of, after we followed their instructions on what we need to do and when, non of the employees can give us straight answers and everybody is talking in different terms. We are sent from one person to another to make payment arrangements for the invoice that was incorrectly allocated to the account, why should we be held liable for an invoice that MTN has done incorrectly!!