One thing that has twice reimbursed my fare completely is the EU strike rule... Air France put me on flights thst got me there almost as fast as the original itinerary during one of their seemingly semi-annual strikes, and after weeks of runaround they've paid it all back. In my experience it's more about tenacity than legal acumen... if you know you're in the right and don't give up, and you can point to the rule or law, they eventually acquiesce. I feel like using this service would mostly help of you don't want to deal with the hassle yourself, but for me it's all part of the fun!