Are you sure BOS aren't recommending Quickswitch from First American? They are completely independent to the lender.
You can find out more at [broken link removed] but basically this is a title insurance company dealing specifically with remortgaging - they carry out all the legal work associated with remortgaging - searches etc. However, a solicitor is required for the signing of the loan offer - you can choose one in your area from their panel (recommended) or if you would prefer to use another solicitor you may do so also but you may have to pay - solicitors on the FA panel are paid €140, if you choose a non-panel solicitor who charges more than this it is up to you to pay the excess.
Many lenders covering the legal fees use First American as they charge an all inclusive flat fee of €999 and claim to complete the transaction within 10 days (realistically though, you can expect for it to take longer so be warned!).