How Do I Renew An Expired Domain Name?

I bought a domain name a year ago, and the person I built it for didn't read their emails and it has now expired.  I looked at the email and it says: If you mistakenly let your domain expire, you can still renew kingscoachluxurytransportation.com with enom for an additional year by clicking here: https://www.google.com/a/cpanel/domain/renew-domain/kingscoachluxurytransportation.com.   But it won't let me renew. I cannot find a google contact, and when I called enom - The domain host they gave me an email. Nobody has responded to that email.... in over 10 days. I am at a loss here. Does anyone know where to go next?