It seems incredible I am replying to this thread today because the coincidence is too real and while I posted on it previously I had no knowledge of this at all:

My friend text me this morning to ask me about Conrad Algarve because he has over £4300 (GBP) of unknown charges made to his Amex card by the property. Correct charges were around £150 as it was a points stay.

Something well and truly bizarre is going on there.

He’s only Blue and given the excellent customer service I’ve found with Amex I have told him just to get them to query it than go back to the hotel. If this really is a data leak, fraud or a very very peculiar series of similarly timed mistakes (that’s so unlikely!!!) then Amex will probably have seen this before and can do something about it. Many a BA Amex goes through that hotel!