It's possible that the notice wasn't on the system at the time you booked if BA are saying it was from 22 November onwards. The Rep in resort has to go to monitor the work, assess how much noise or nuisance is being created and then a decision is taken whether there should be a prior notice go to the Operations Department and systems. Then it takes time to create it and load the information on the system. So I think a week wouldn't have afforded enough time.
I doubt they would advise before the work actually started as often dates get pushed back for one reason or another.
It's also possible the work may be almost completed by the time you are due to travel or your tour operator may have been given different information by the hotel. Yes, it does happen! The hotels are not very forthcoming when they're about to disrupt their guests and prefer not to tell the tour operators until the very last minute or not at all.
I recall visiting the Atlantica Hotel in Limassol many years ago on an educational visit and discussing with them how they had closed half of the restaurant because they suddenly got the idea to build a bridge over the swimming pool. No advice, no nothing with guests up in arms! Then the hotel wondered why they were getting their rooming invoice payments reduced for compensation we'd had to pay out to the customers....
Shell
Limassol, Cyprus