2021 - What I did today

JJB, can you ask their vet for some proper flea treatment - I don't think some of the off the shelf stuff is very good - if that's what they're using.
Sarris has a few cats - maybe she can recommend something?

I can - it's something I was constantly having to battle with at the old house, as there were so much of the little things outside. The best instant stuff is Capstar - a tablet that you give them and the fleas die within an hour or two. Then top up with spot on stuff - Advantage has worked really well for us for quite some time now, but it's good to change around.

Vets can give injections too, which are very effective, but I've not personally tried that.

For floors and material - hoover daily if not more, and spray with Indorex, daily. Materials - clothes etc, was any that have been in touch with fleas.