Cant cancel contact out of term cut line

I don’t understand why a contract cant be cancelled after the 24 month contract. The fact that there might be an outstanding amount should be irrelevant. The agreement was only for 24 months. The outstanding amount is half due to the fact the contract is over and still beign charged. No the lines have been suspended due to a outstanding amount even though we paid last months owing. I have tried since October to cancel the contract ********** 616 ... everytime hitting roadblocks. Very bad service