You can use Quickswitch from First American - they charge an all inclusive flat fee of €999. I'm sure if you asked your solicitor they would match this - make sure that you mention their fee includes everything - VAT, outlays etc.
On a €300k mortgage I would gconsider that €999 package to save hassle .
If its a €100k mortgage its too high but use it as a basis for haggling. A €100k mortgage should be around €700-€750 including redeeming old mortgage and stamping the new one and the rest of it .
We did this recently when we took a fixed rate with the National Irish Bank. They paid us €1000 towards legal costs which came to about €1200 in total (solicitor charged us €750 plus vat). Don't forget that if your mortgage is over €254,000 then you have to pay stamp duty of 0.1% (i think that is the correct % figure).