Hi Nigel,
If you wanted to you could send your post to them by Snail Mail at this address: Yahoo! Inc.
Customer Care - Privacy Policy Issues
701 First Avenue
Sunnyvale, CA 94089
(408) 349-5070
or go to Yahoo and paste it into Security feedback, although I think a letter or call would carry more weight.
Sad situation indeed when you think that Yahoo and other sites share your personal info with various Companies...but at the same time they do secure your emails and a lot of people hold them to that agreement but I would be happy to see them work with this grieving Father.
You, however, have offered a fair solution.
Blessings
Jude