unhappy with the service I received

Last year I took a data contract with 084145 and remember telling your agent I only want a 12mnth contract he said yes, ok, dont worry its sorted out only to know when I called to cancel your agent says no it is a 24 month contract? Then on numerous occasions I tried calling your cancellation department and for hours no one picks up that line so called your call centre there no one can give me an email address to send my cancellation letter nor can they send an email to cancellation department for someone to call me? After being with cellc for so many years I must say this is the worst service ive ever received, I want both my contacts cancelled with immediate effect.