Trying to create an account for American Water (South Orange)

I want to register for online access to my water account. The registration form says to enter my account number -- the last 12 digits after the dash -- but my account number on the printed invoice only has 8 digits (10 if you include the numbers before the dash) and I keep getting error messages. I've tried various permutations of leading and following zeros with no luck. Has anyone else encountered this and gotten it resolved? Or do I just wait until Monday morning and call for help?