Continuous Billing After Cancellation

I have requested cancellation of my rain subscription in February, to date I have been informed that the cancellation has been successful and my device has been collected yet for the past two months I am still being billed by rain after being informed that my last payment would be in April as there payments are worked as arrear payments! I have logged numerous calls and emails with Rain and have had no success! Does this mean that I now need to cancel my bank card and get a new one so they can no longer bill me? Pathetic customer service!