My Wife and I took out a 5 year fixed rate mortgage with the Chelsea Building Society last year, and at the time we had no intention of paying off the mortgage early and the early charge was not a factor. Now my Wife and I have decided to buy a plot of land and do a Self Build, unfortunately, Chelsea do not offer a self build mortgage and as a result we will have to leave Chelsea for another Lender. The issue I have is that a 4% penalty is excessive given that the BoE base rate is 0.5% and that Chelsea will borrow funds at a much lower rate than 4%. Can I challenge the rate on the basis it is excessive? Thanks