I used the services of AirAdvisor after I tried unsuccessfully to claim against easyJet for a delayed flight. It was worth the fee I paid, as I got zero trying to claim myself. After this successful claim, I then decided to ask air advisor to act on my behalf against United Airlines, who had ignored all my communication regarding a claim for a delayed flight from Barcelona. It took a significant time as the case had to go to court. They kept me informed of the proceedings and yesterday I received a cheque for 600 eur. Airadvisor took 50% fee because of lawyers involved. I would definitely recommend this company even though no cheap - successful on both claims.