Ya, that's a tough one. And I'm not trying to just argue with your or say "You're Wrong!". My goal is just to point out the specific DL terms and conditions which make it basically impossible for them to lose on this one. My guess is the full fare code offered by Senturia was different than what you found on DL, making DL right according to their terms and conditions. Even if it was the same, there was no way to know since Senturia didn't show it, so you don't have the proof to argue with DL.

Everyone gets angry with this policy, and I agree it's more or less a sham. But save your time and energy because it will go no where with DL. It's basically a marketing tool for DL, and they have written the rules so that they can not lose.