I would have said that a minimum fee about €500 plus V.A.T. and outlay is about normal here. This is a full remortgage and settlement of an existing mortgage. A far cheaper transaction is to get a top-up on an existing mortgage, for which the solicitors fee would be as little as €100 plus V.A.T. (and some lenders do this in-house, so you don't even need to get a solicitor).
Regarding setting a fee "ceiling", this can only be done based on agreed assumptions about the workload. If there turns out to be extra work, it has to be charged for.
It is not uncommon for these transactions to involve extra work (for example, there could be two or three existing mortgage accounts, plus a car loan and a credit union loan, and the new lender requires the solicitor to clear all out of the new mortgage cheque and furnish evidence of this; OR the client might have built an extension since the place was last mortgaged, and the solicitor now has to chase up an architect's cert double pronto, becuse the client never bothered etc. etc......) so the figure of €500 plus V.A.T. whcih I cited above is more a floor than a ceiling.