Right! I can tell you exactly what to do as I had a similar experience.
You could get your hair dyed to a darker colour (I did). As he basically ruined your hair you didn't have to pay him and I'm pleased you got your money back. I asked my hairdresser for a full head of bleached highlights but got bleach permanent colour which was what I did not want.
It will have to grow out/be cut out. Cutting it out is harsh though and a lot of hairdressers will advise you against it.
Go to reputable hairdressers from now on and have consultations. If you're not happy don't use them.
You can try Aphoghee and other treatments (I bought this but never ended up using it!).
I was told by hairdressers after this to:
use a mask once or twice a week and with a conditioner afterwards. I currently use Davines Oi Oil shampoo and conditioner and Garnier Ultimate Blends Masks but have used more expensive ones. I also use Pantene 3 minute miracle during the week too as not as strong as normal masks.
My saviours after washing are:
Redken One United (treatment spray)
L'Oreal Pro Fiber Recover serum (discontinued but you can find on Ebay)
I also let my hair dry naturally nowadays and rarely blow dry it (apart from at salon).
It will be an absolute pain to grow out and treat and I recommend you get regular cuts/colour for at least the next 2 years which for me would be every 8-12 weeks. My hair I've only recently started having highlights on it again but it's been about 2 years since it was damaged so I presume a lot of the damage has grown out.
It's good you got your money back but I'd be trying to ask him to get a darker semi permanent/permanent colour on top. Depending on the damage, I'd also consider seeing a solicitor for damage to your hair. You told him your hair was weak so he shouldn't have gone ahead with the bleach, or should have warned you of the outcome.