...I can't get rid of the buggers and poor dd is getting bitten far too regularly 
I use the drops in between their shoulder blades every month (stuff bought from the vet or pharmacy) and have sprayed the whole house using the spray recommended in a large pet superstore (hoovered b4 and after treatment). Wash all linen regularly. It does my nut when I see yet another bite on dd.
Our two cats are part of the family and we love them, but this can't carry on, poor dd is always scratching the bites and gets nasty scabs as a result. It must be so uncomfortable for her, not to mention embarrassing for us.
DH and I don't get bitten and the vet nurse I spoke to suggested its due to dd being closer to the floor.
What else can I do to get rid of them? It was never bad when we lived in a town but terrible now that we are in a rural area.
Thanks