No one, EXCEPT Avast Customer Care (see attachment)
You can submit your feedback in "About Avast".
I DID submit feedback when I first encountered the problem with being unable to renew my registration 3 weeks ago.
I also opened the support ticket that's shown in the attachment on my previous post on the same day.
I was hoping that my Avast would keep working as promised after its expiration date (today), but unfortunately that didn't happen.
So I came back to this forum, hoping that maybe someone might have found a solution for this problem over the course of the past 3 weeks,
but obviously that didn't happen either.