pathetic service cancellation department

Both my contracts expired 4 months ago I did not want to re-new however was pestered into renewing by the call centre guys. So I renewed only the 1 but I am being billed for both for the last 4 months. Every time I call they say it will be cancelled ASAP but nothing happens they can't even give u a reference number says it's all on the system. I requested for management to call me bk but nothing there service is pathetic !!