I am having trouble getting a reply to my application for a new license key
Try contact avast programer vlk@avast.com, he will be the best help with you issue.
Do you speak about the Home or about the Pro versions?
If you speak about the Home version, try to register with another e-mail address
You don’t apply for a new license key, you either register in the case of the Home version avast! 4 Home Registration, or in the case of the Pro version purchase a new license. In either case the registration should be emailed to you.
Watch out for email spam filters.