No comunication when trying to cancel my account

Since 19 August 2015, I have sent 2 emails and phoned the call centre 5 times to follow up on the cancellation of my account. To date I have not received any reply or email confirmation on the receipt of my cancellation request and every time that I phone, I'm told that my request should be with the cancellations department and that I will receive a call from them once my request has been processed. It has now been 4 weeks without receiving a call. I will now need to contact my bank to ensure that the monthly debit order does not go off my account again, I'm sure that I will then receive a call immediately after the deduction fails.