If you live in Wales, especially if you live in the proposed 'Metro' area or in the current Valley lines / City Line / Vale of Glamorgan line area, the best course of action is to contact one of your 5 Assembly Members. Everyone has one constituency member and 4 regional members. Find your members here:
http://www.senedd.assembly.wales/mgFindMember.aspx
Contacting a Plaid or Conservative member is best, or a Labour member that has been sympathetic to public transport, such as Jenny Rathbone for Cardiff Central or Lee Waters for Llanelli. Contact your MP if they are from an opposition party. If you live in VOG contact the Welsh Secretary! Where AMs can fight is on the complete lack of
any transparency that there has been from Welsh Govt / TfW in this whole process. It's despicable that no details are being released for consultation until
after the contract and deal is signed and sealed and nothing can be changed.
I also doubt the Unions know anymore than the general public do about the extent to which the Welsh Govt wants to convert the Valleys to trams. The RMT has been suspiciously quiet since they belatedly realised that WG wanted to transfer control of the Core Valley lines to the private operator of the new franchise, but since Carwyn Jones announced that they'll be keeping a guard on every train, they've shut up.
Gareth Marston will no doubt say it's too late and there's no point, WG will do what they want anyway, but it's worth a try at this late stage.