Domain Mapping Issue

I have a serious issue from Zoho Support. I somehow go the domain mapping incorrectly and now I can not log-in my account. How to I undo the problem?

I get this message.

404 Not Found

The server can not find the requested page:

www.support.amtechsystems.com.pk/support/amtechsyshelp/ShowHomePage.do (port 443)

Please forward this error screen to www.support.amtechsystems.com.pk's

Please help?