I have an identical issue with Unicom as CAG member M1JWR (title 90days) March/April 2012. I.e. Unicom imposed their own contract after company merger.
The information I am getting from Ofcom is not quite so clear cut, because 5 months has passed since being advised (identical letter to that quoted by M1JWR) it could be interpreted as acceptance.
I can see from the thread that the 2007 Elite Calls contract is valid, and I have persistently advised Unicom to that effect. I have not agreed to accept the changes verbally or in writing.
I cannot see whether M1JWR had a successful