Same problem, wanted to come back after some years and error 11002. Actually first it was 11001, now it is 11002... played through steam back in the day, tried changing password but apparently that only changed the password for the gamersfirst account, not the steam account I used to play on (they have the same email probably). I had almost 500 hours in so rather not make new account.
Made a ticket, ID #79625
EDIT: I can login through gamersfirst account just fine, but that is empty because I always played trough steam