I have just read Tinks thread and have a similar problem...
I took Oli to visit my uncle and his cat because I had to house-sit. Anyway, a couple of weeks later we noticed black bits on his bedding, so got some Frontline spot on. The vet told me I didn't need to spray the house because we hadn't actually seen any fleas. All of Oli's bedding and our own was washed on a 60 degree wash. Anyway, the Frontline didn't kill all the fleas (probably because we already had it in the furniture!) and four weeks later the vet suggested we treated him again. I did, but also sprayed the whole house with a household spray from the vets. It is now about three weeks later and he still has fleas!

We comb him atleast twice a day and the last few days we have been finding up to five fleas a day on him.
I have ordered another household spray, but seem to be giving up all hope of getting rid of these horrid things.
Does anybody have any suggestions??? Help would be really appreciated.
Thanks,
Tanya