Under EU 261, UK 261, and similar Brazilian/Turkish laws, you may be owed up to €600 per passenger for delays over 3 hours, cancellations, or being bumped from an overbooked flight. AirHelp files the claim, fights the airline, and pays you. No win, no fee.
You may be owed compensation if any of these are true:
Run AirHelp's free eligibility checker - paste your flight number and date, and they'll tell you in 30 seconds whether you can claim. If yes, they file for you. If they win, they keep ~35% as their fee. If they lose, you owe nothing.