Solicitors made mistake with will

My grandfather inherited money 2 years ago from a friend who died. A year and 2 months ago he got a letter from the solicitor saying that they had miscalculated the amount he should have been paid and that he owed them 3,500 euro. The letter included a list of all the beneficiaries of the will and how much they got. The solicitors admitted it was their mistake.
He didn't really have any way of paying the money back and since he heard nothing more from the solicitors he assumed they had written the mistake off to insurance or something. He has now received another letter looking for the money. Is he legally required to pay them back even though it was their mistake?

i would think he is entitled to it.. they did after all make the mistake and overpay him

So lets just say that you had hired a solicitor to do some work & subsequently paid him €4k.

Some time later you realise that you had made the cheque out for €5k by mistake.... you then go back...expecting your money of course. What do you think should happen?

ninsaga

as a consumer i would then have rights to be refunded this extra 1k