I recently started an account with them and I find the options very limited . Almost same with support , after calling 4 times in a day i only got a email in reply with a canned response .
Even google does not reply you immediately. About 3-4 months back we faced click fraud issues in our PPC campaign. We mailed several times to google, but only received email after 3 days. Can you post the problem which you were facing with Yahoo account
could you get a better traffic with YPN ? was your problem solved ? I think google also doesn't gives you response quickly . It too takes time I think ..