Have you checked the Spam filters in the receiving email clients? Often they seem to end up there.
Thanks for bringing that up Sanenet.
Yes, this happens with some frequency, and may also apply to email sent from our customer service team.
So if you ever feel as if it's been an awfully long time since you wrote AdWords support, and you're getting a little miffed that you haven't heard back, well, please check your filtering. Such filtering is behind many 'no response' complaints.
;) AWA