You need to keep vacuuming and treat the cats as eash says. But if you have fleas in the flat you may have to use a chemical spray to get rid of them. The sprays are very effective
Try petmeds.co.uk as they sell frontline half the vets price. if you treat your cat every month they wont get fleas or ticks. the fleas are probably in your carpets and just keep breeding. to get rid completely you will need to treat your whole flat . Try a local company
You really should apply frontline regularly to your cat, it must be frontline, the cheaper spot on treatments just don't work at all, they're a waste of time, buy a spray from your vet to treat your flat, and as long as you keep up the frontline treatment, you won't have a problem again.....hope this helps!
Please do get some frontline treatment for your lovelies... it's not fair to expose them to nasty critters like fleas and mites. Frontline is easily available on the tinterweb, at a fraction of the price from the vet and it will make your lovely cats lives a lot happier, honest ! I get mine from PetVetCare... cheap and rapid delivery too !
Fleas can kill a kitten and seriously harm a poorly cat, as well as not be too nice for any humanoid visitors, so please get some proper treatment for your lovely cats.
Get RIP from your vet.......spray EVERY room thoroughly. It will kill fleas, and their larvae for at least 6 months. it really does work. Also...DO vacuum,,,every day for the next few weeks if you can.
On the odd occasions our cats've brought fleas into the house, I spray them - and the home with Nuvan Top from the vets. It's brilliant, but cats hate aerosols, so I put mine in a carrying cage, then spray them, being careful not to direct it towards their faces. You won't see a flea for miles when they've taken that stuff in.