This is what you would probably call these secondary domains under your account: Addon Domains are domain names that point to subdirectories within your account. To my knowledge, you should not be able to access it that way, if it is set up as an addon (then again, I don't know what you're using, Plesk, cPanel?). One suggestion could be to do a redirect from site2.site1.com OR site1.com/site2 TO site2.com. I would also suggest contacting their tech support, if it's free or affordable, assuming you can't fix it yourself. Make sure you do a FULL backup before you or they get their grubby hands on your files and start changing things!!!!! Also, document changes to other settings so you know how to change things back.