I just flea combed Fizz every single day for several months with a flea comb and drowned those suckers in a cup of dish soap water until I could flush them down the toilet. It took a really long time but it eventually worked. I was afraid of using any flea solution on her so that's the route I went instead. I will say, whether you use flea solution or not, you're going to want to put down borax powder EVERYWHERE and especially on carpets, fabrics, floor cracks, etc. Anywhere the flea eggs can hide. My whole apartment looked like it had snowed for a while I got so over-zealous about things, even put it between my mattress and box spring. I washed and machine dried my bedding and the rabbits towels in a two week pattern too to kill any eggs. I maybe went a bit overboard but if you don't kill the flea eggs, even if you get rid of the original fleas the problem is just going to come back again. So you're going to want to de-flea both your rabbit AND your living area and you're going to want to stay on top of it until you're sure there's no chance of a come back.
You can buy a big box of borax powder in the detergent section here. I'm not sure how available it is where you are but its basically salt that's safe for pets and humans if they get it on them. It eats through the eggshells and the exo-skeletons of the fleas. If you don't have borax you've probably got something similar because its a standard 'old school' way of whitening clothes. I wouldn't put it on your rabbit but it should go on just about everything else that might be a flea egg haven.
(I also heard that rosemary powder was something fleas don't like. Same for sage powder. I did put a bit of sage powder in Fizz's cage on her bedding the entire time too but I don't know, other than smelling good, if it helped or not)
.....and now I'm feeling itchy lol