Unfair billing and treatment of client

Due to the sale of my property and relocation to another property I gave ADT 45 days notice around the 15th Dec 2014 to terminate my armed linked response contract at the end of Jan 2015. I was billed on the 20th Dec 2014 for an amount of R 1400 for cancelling. When I queried this I was told that the new owner has to take over my contract otherwise I get penalized. I took over the same contract from the previous owner of the same property on the 30th Jan 2014. it is my right as the consumer to cancel a contract after twelve months re the CPA. I wrote to ADT customer services by e-mail requesting that they look into this more than a month ago. To date I have received no response. I sent ADT the contact details of the new owner property so that he could be contacted to take over the contract- I have had no feed back except for another statement showing that I must pay this penalty for early cancellation- when I had run with the contract for 12 months. This is poor service and bullying tactics in my view.