BT 18 month contract

I recently moved back into the family house (long story). As I had a 12 month contract with BT from my previous house and as I had almost 6 months of the contract left I contacted BT to look at the options of either transferring the line or canceling the contract. The family home already had a BT socket but it hadn't been active for over 10 years as we had NTL/Virgin cable installed. I was told to move theline would be £129. When I explained about the cable they said they could do it for £29. The cost of cancelling the contract was £166. So I thought £29 plus 12 months rental at £12 a month. ( Sorry, I should have explained. Moving the line would mean resetting the counter on the contract to zero) was a slightly better deal then forking out £166 to cancel. So I rang back to tell them to go ahead and move it. Then I'm told that the price of £29 only applies if you agree to an 18 month contract:eek:. Reluctantly I agreed as I couldn't afford the £166 in one go. So the phone was connected (remotely) last week. Today I get my DD letter/contract which states that in order to keep my low cost of £29 for the 18 month period I have to make a minimum of 10 calls a month:mad:. This was never explained to me when I agreed it over the phone. Do I have any legal recourse over this? We are very low phone users. What happens if I forget one month and only make 9 calls? BT "your aving a larf":D