i think you'll have to go through their ticket system. on wex.kayako.com, you can go to "start a conversation" and choose from the menu the most appropriate issue. i would go with "problem with login to account."

also, i would avoid using IP whitelisting, for the exact reason you mention. most people don't have static IP addresses, so i wish that exchanges wouldn't even offer this option. you are best off using a strong password combined with 2-factor authentication on your phone. once you can login to your account, you should definitely remove whitelisted IPs and stop using the option.