N&P 10 year fixed not actually fixed?

So we looked carefully at the small print and it says because of the merger with YB they reserve the right to change the interest rate until November 2014.

It's 4% at the moment, but I guess they can just up it to whatever they want next year? (You are allowed to leave if the do that)

Do I need to go back to the drawing board to find another fixed rate, or is there something I cam do/some right I have based on their advertising a 3.99% 10 year fixed?

Thanks very much.