coolbeans
You will probably find an approach to GATCO unhelpful, especially if past experiences at EGLL are anything to go by. ATCO Unions are there for the benefit of the ATCOs, not the ATSAs.
I presume from your posts that you don't have Union representation - maybe a chat with PCS, (rather than GATCO/Prospect), for their view on the situation might be a good next-step? You should also "go prepared" for your chat with your Management - get all the available info from CAB which was quoted to you first, and check it out thoroughly, and be sure you understand the in's and out's of your terms and conditions within your Contract of Employment, plus any local agreements.
Be sure of your facts before entering the fray - these issues have a nasty habit of biting back!
Good luck!