Please don't EVER use ANY Bob Martin stuff. It's terrible. Their flea collars and treatment have caused severe illness and deaths in animals.
A couple of years ago I THOUGHT I saw one
loan flea on my cat. The vet THOUGHT he saw something too. Neither of us were sure, but he said best to treat it anyway
I got a spray from the vet called 'RIP Flea' (yes, seriously!
) that you use to treat the house. I won't lie. It's a pain to do, but fortunately I've only ever had to do it once. He treated the cat in the surgery on the day.
I couldn't understand how it happened as she's treated with a prevention treatment every three months, however I had been using Advocate and the vet said that a lot of cats seem to be getting immune to it. I use Bravecto now.
You can buy RIP Flea on Amazon and perhaps pet shops might have it, but ask the vet what's the best thing to treat the cat with.