Yes, you can freeze and unfreeze your credit at each bureau via the phone, in addition to by mail. Snowcap.Me only supports freezing and unfreeze via the web, but if you’d like to try the phone-based method, here are the phone numbers to each bureau:

TransUnion 1-888-909-8872
Experian 1-888-397-3742
Equifax 1-800-685-1111