****med by network accs dept

I have used this service 4yrs back. It was a month to month contract. This contract was cancelled after 4ys I get a debt recovery attorney call me asking to pay a fee of 580 for admin fees. I neva used this service since 4yrs. Today they contact me and say my service is still active. What a shock to me after a cancellation was done 4yrs ago I get a call today. I was asked to do another cancellation and was told someone from acc will call me. I am surprised why shud acc dept call me when I neva used the service. In 4yrs I neva heard from them neither was an emailed sent to me. How can I be billed for a service that was not given. This is a huge **** pls I need answers to this service. Can someone pls contact me. Most untrustable network.