Update: finally got a new cert installed, involved a lot of go between support and back-end support. There is no ' correct' interface to upload the cert, you'll have to go through the windows auto discovery->REGISTER DOMAIN FOR WINDOWS AUTO-DISCOVERY->' select your domain' ->upload the cert (don't worry about cname validation)-> punch in password for the cert(make sure it validates and reads it!)->upload.
Once uploaded, tell support and they'll tell backend to update the cert by...hand.
