still not deactived after 8 months of canceling the line

Worst service ever, i cancels my land line in the end of January 2018 and October 2018 its still active and shows a bad credit score on my name as a non payer with outstanding dept. i contacted them 6 months ago regarding this problem and they just told me its out of their hands and will go off some point or another and they will depute it , 8 months later its still on my name and they cant even tell me when will the line be canceled off my name.

i canceled this line because of bad service delivery now i cant even get this off my name. this is the worst company ever.