First thing to do would be to get your house valued, if your loan to value is less than 92% then you should try to switch now just in case property prices fall further.
There may be a breakage penalty from BOSI and legal fees for the switch but this could be a small price to pay to get a variable rate of around 2.65% instead of a fixed rate of 6.1% or variable of 4.3%.
You should have a proper mortgage valuation carried out - should be about €130. Make sure the valuer is on the approved panel of all the lenders and has professional indemnity.
If your LTV is >92% then I'm afraid you will be stuck with BOSI.