The six things a written claim has to contain, and the two that make airlines settle rather than stall.
The phone call and the airport report are not the claim. The written claim is. It needs to reach the airline within the deadline for your trip, and it needs to contain enough that the airline cannot bounce it back for “more information”.
The two things that change how the airline responds: citing the rule that applies with the correct current limit, and arguing your list up to the cap rather than accepting the airline’s depreciation table. A claim that shows its arithmetic gets handled by someone who can approve it.
Build your letter → Free. Takes about ten minutes.
Whatever the airline’s baggage page says it accepts. Most take a web form or email; a few still require post. Your airline’s page on this site lists what we have verified.