Originally Posted by weero

LH is not in charge for that segment (even though they created the problem). You had a boarding pass and hence were entitled to transport if the flight was still open. Hence this is an IDB situation and you should file it as such with the DOT if UA refuses to compensate you.

I'd simultaneously push for LH compensating you for not fulfilling their contract of travel, especially as it was sold as one flight number as you mention.