For the umpteenth time
Please read what your contract states about Collective Agreements - specifically the part that says
"as amended from time to time" 
That negates what you are saying below as they have covered off the need to have a personal notification
Quote from Hifler14
Also if collective agreements are contractual, surely that would mean that every time there is a change to the collective agreements, each individual crewmember would have to have personal notification from BA of an ammendment to their contract? And in umpteen years, I have never had one.