After a bad delay experience (worse than most cases, because right in the middle of the night), I decided that a claim to the airline was totally justified (Air Europa). The company rejected the claim on incorrect grounds (weather conditions, while no other flights from that airport were actually delayed significantly), so I decided to go ahead with more formal action and contacted ClaimAir. To be honest, I suspected that this action would also be rejected, so my expectations were rather low. I did hand all relevant data over to ClaimAir, including travel documentation, but also the actual flight path, with time data over the full journey and weather reports from the corresponding date. After some time I received the message that AirEuropa was still unwilling and legal action required. I agreed to this. None of this cost my even a cent of money. ClaimAir then met their promise and indeed were able to recover the fee as foreseen by the EU regulations. I was again nicely informed and received the fee minus the exact promised proceedings cost within a week. Thanks to Claim Air!