Did you start with http://help.yahoo.com/l/us/yahoo/abuse/
http://help.yahoo.com/fast/help/us/sbiz/cgi_abuse
http://www.logbud.com/dns?host=yahoo.com
"Yahoo general phone: +1 408 349 3300" X1572
#2
#3
reportabuse (at) yahoo-inc (dot) com [email concealed]
Then it hangs up.
#2 Gives 408-349-1572

I did an 8 then a 0 and eventual...

[ more ]