Originally Posted by
serfty
Airlines don't like the regulation and generally try to delay, obfuscate and otherwise pretend claims relating to it do not exist or are invalid.
Ticket stock (ticketing carrier), flight number (marketing carrier) are irrelevant when it come to EUC 261/2004.
It's the operating carrier who is liable - so KLM - and they have lied to you (it's nothing to do with DL)
Contact them again and do not be put off.
In my case operating carrier was DL and KLM gave me the voucher (only usable on KLM.com or cash) - so generally yes, but with the DL/KL/AF combo itīs a little confusing due to their handling of customer service for each other