There is no better flea treatment then frontline its amazing. I have 4 cats and i have no problem at all. Frontline is availble from your vets.
Back in the days when i just had one cat i used spot on for flea treatment. (which is always sold in shops like tescos asda etc) i was covered in flea bites and had to throw away alot of bedding as it got too out of control. its not worth the risk even though it is cheaper i can 100% say you might as well be putting water on your cat as it doesnt work at all!
stick to frontline you cant go gone!