Delusional, best describes many of you with respect to the legalities of your working relationship with Norwegian. Is there a signature from Norwegian on your agency contract? Do the terms "seniority" and "transparent systems" or similar, appear anywhere in your contract?
The Scandinavian core group are the only pilots having direct employment with Norwegian and associated employment rights. This group was unilaterally divided into three divisions during the strike (possibly illegally) and has a collective agreement with Norwegian for three years. After which, they too will become employees of an agency.
Norwegian is not obliged to give an agency pilot three months notice - they simply instruct the agency they no longer require your services, and the agency gives you three months notice, not Norwegian. The agency may find you alternative work during the three months notice period. If they do not, a clause in the contract indemnifies the agency from your financial loss a result of any action by the lessee airline - read your contract.
Who would you take to an Employment Tribunal? - certainly not Norwegian, they were not your employer.
BALPA and SELPA can only collectively negotiate with an employer. Norwegian has no legal requirement to comply nor honor any agreement reached between a pilot union and their employer agency.
Welcome to the Bjorn Kjos world of employment rights circumvention. A world with no lights at the end of any tunnels.