Elephterion (Envision Developer),
This is a very SERIOUS ISSUE! what we have here, and my best guess is that its related to the SSL secure connection or the permissions regarding connections or in the certificate of the site itself.
This is a MAJOR ISSUE, its not related to some people using some browsers or clearing the cash, its very obvious for most of the community.
If EA had dropped support for this game, it must inform its users and have to make a clear disclosure for the community and must stop the payment system, failing to do so will put EA with a lawsuit against the community.
This is a statement from you on the 11 of April announcing a new login system:
https://forums.ea.com/en/commandandconquer/discussion/219088/new-ea-login-page-redirect
You as a developer and the company you work for have full responsibility for its users!
So I suggest that you really have to move your ---- very quick, or you will loose your community by the end of the year, and maybe your jobs!