Firstly, I want to say a massive thank you to all who answered!! It really was appreciated and I took note of all the suggestions. Scott in particular your advice of getting the transcripts was a particularly smart move in my opinion and probably the route I would have gone down had this continued.
In the end I managed to track down the employee who sent the confirmation of rate and fixed term period to my solicitor. After getting him on the phone and saying that I had his letter to my solicitor (with his signature on it) things rectified themselves very quickly! :-) Anyway, this is now fixed. Halifax have confirmed the correct rate and period of fixed term (4.99% for 2 years) in writing. They have also given me a new agreement to sign with this correct rate. I sent this back to them yestoday and they have got confirmation they received it.
Anyway, once again, thanks for the trouble you all took to compose the replies. great bunch of people on these groups! :-D
Best regards, John Smith