OMG! Thank you so much for the link.
It is 100% Delta's fault. They really screwed up royally this time and it is all fully documented!

At this point I think 2 GUC are too little of a compensation. Even if they put me on another flight, in an inferior class of service, there is still the matter of making me trot between terminals twice on Christmas Eve and the pain and suffering of suddenly feeling that I was not going to spend Christmas with my family and miss my flight from London.
I'm pretty sure a jury of my peers wouldn't get a very favorable impression of the company.

One more thing: you wrote "since November". How do you find the publishing date of that timetable ?