Not able to stop unauthorised subscription

I noted on my cellphone account that I have been paying for a subscription, which I never authorised. I contacted the call centre on 14 August and again on 9 September 2015 to cancel and arrange for reimbur*****t. The subscription still continues and I need to know when the money *******ly taken from me will be reimbursed and the subscription reversed. The call centre does not allow any calls through today. I believe this is a business to be avoided at all cost.