incorrect activation

i have renewed my contract with mtn on the 26th of december 2013, as my contract stipulates to expire on the 26 of december 2015. MTN refuses to cancel my contract due to error on they side. they have activated my contract to only expire on the 30th of december 2016. now i am being held liable for a contract that i cannot pay due to they incompetence.<br> <br> is this fair on my part i have paid for two years now because of they staffs error i am being held accountable and should i refuse to pay be blacklisted. i have informed them of this for months with nothing being done about it.