Bad Service

I have been trying to cancel an account that was opened a while back. I can not get this contract cancelled as the shop can not assist me, I have to phone in. When I phone in, they can not help me because I do not pass the security questions. Went back to your shop to verify all my details and have a print out of everything that is on my contract. Still when phoning they tell me I do not pass. How do I know that your operators are not selecting wrong information??? How is it possible that 3 times in a row I can not be verified by your call centre??? How in the hell do your customers cancel contracts???? You are very happy to take my money, black list me if I miss one payment on this stupid contract that I do not want because the device was ******!!! do you care... no. I need this resolved a.s.a.p. or I will be taking this further as you owe me quite a bit of money and I assure you, you do have all the recordings and emails I have been sending. Patiently waiting for your response