OnAir bad service

Bought decoder and was sold to me by false information. Returned the decoder and cancelled contract after months of trying to resolve the matter. Finally contract was cancelled but on my credit score it shows l owe them. How can l owe for a service l didnt get and l cancelled everything on time as per their conditions. Called them and they agree l dont owe them but why not remove my name on ITC? Please clear my name on ITC as per Experian advised.