I used to work in this area up here so what I'm typing is 100% applicable to Scottish law and is not that different down your way, get it checked out by a cab. Also i only read the first post on this thread.

Firstly, council tax is collected on a summery warrant, no court appearance.

Warren, the chances are this company will be acting under instruction from the council, not having bought the debt. S/warrant stuff doesn't work like that, a Decree does.

If under instruction then the council does still have influence over them, when you paid your money to the council did you pay the full years arrears? If so take your proof of payment to the collectors office and show them its paid IN FULL.

If not find out what the remaining liability is and pay it. If it needs to be amended to take account of any reduction get the council to sort it then provide the proof to the collector.

any help to you?