Nexgard combo? Need to annihilate fleas!

[themiffy]

Never saw fleas on our cats until we moved- prev owner had a cat farm I think, and the house was full of both fleas and cats, and I cannot now keep on top of the fleas!
Have tried advocate and advantage and flea bombed the house, plus using Indorex. But still, I see them!
Saw a thread recommending Nexgard but it’s pricey, wondering if others have used it and can tell me if it’s worth the price?

What has your vet advised? Advocate and advantage have the same flea treatment in them so if 1 doesn't work neither will the other.

Your vet could advise what is effective in your area. I use stronghold plus on my cats.