It does seem unfair. I guess like all businesses they have to make the money back that they have lost somehow. In the UK the banks do not have to pass on the interest rate reduction to the customers in line with the Bank of England base rate. In fact they are not doing. Most loans are linked in some way to the base rate and your loan will move up or down depending on this. Kind of strange that your rate has nearly doubled. It should have stayed the same as a minimum if not gone down. I would look at the terms that you signed the loan on. They can't do that in the UK, but then HSBC isn't a UK bank so hey ho.