help to sign into firefox sync on new device - user login email address doesn't exist for ages but not possible to change it

I had same issue years before. New device, trying to sign in and it finds it unusual behavior, so it doesn't let me in, it rather sends a confirmation email to primary email address which was closed down by nokia ages ago.. I've added my new email address to my old account, but of course the confirmation email is not sent to that one, when changing the primary email is still impossible. I do remember that last time I had to contact someone from firefox to help me through this, but I have no clue how did I find that contact in the first place? if anybody please could tell me, that would be really really appreciated. I bought a new device to work on it, and I have so much stored in my firefox sync account (new device is android, hence I post here)