Unless you have the word "tracker" or xx% above european Refi rate written in your main contract, then I can't see any case. For me and others, the mortgage was taken out as a tracker. It was written in black and white in the contract. and at the time when we went onto fixed and told that it would revert to the homeloan variable rate, we assumed (rightly so imo) that it would revert to the variable rate that we had signed up to and which was written in our contract - "xx% above ECB refi rate".
What most people are fight for is the return to the contracted rate in the original mortgage document that is very clearly stated that it is a variable rate at xx% above the ecb refi rate "for the life of the mortgage". The three year fixed instruction should only have amended he document for the three years.
peemac, their 'Prevailing Variable Rate' was another term for a tracker, was it not?? If someone could confirm this for me, that would be great.