My request for asistance was misunderstood. I was seeking refund for downgrade from Business to Economy class on a replacement flight after a original flight [LHR to EWR] was cancelled. AirAdvisor sought and eventually got me the statutory compensation for the flight cancellation - a relative pittance. Even so, the payment I finally received via AirAdvisor came a couple weeks AFTER United had offered me essentially the same amount, but was actually less because AirAdvisor took out their 30% fee. I still have had no action on the price difference between the premium class seat I purchased and the seat I had to settle for on the replacement flight. Maybe they'll do better on that, but who knows?