[statictype]

You could just visit them in a desktop and regenerate the certificate?

[tedchs]

That was not my experience. I had the same problem, and their support would not let me change to a different client cert.

[lambada]

I've done that several times in the past, never had to contact support. Just go through as a new user. It means you have to revalidate your domain ownership but that's not much of a hassle.

[_nalply]

I even used a numbering scheme: [e-mail] [e-mail] and so on.

[stirner]

To do so, you'd have to log in. To log in, you'd need the existing certificate.

[electroly]

That's not true. I regenerated several login certificates before I finally actually figured out how to install the certificate in my browser. You are not screwed if you lose your login certificate. As long as you have access to the email address, you're fine. Use the "Lost authentication certificate?" link on the login page.