Hi everyone
I have had a reply from Sony regarding the spam and this is what they said (stealing a line from CIF)

Thank you for alerting us to spam on Billy Joel's site, we do our best to keep these posts away from the site. We have recently removed posts of this nature, you can help by clicking on the "Flag as offensive" button next to each post.

Kind regards,
D2c, Feedback, Sony Music

So flag anything that you find offensive, specifically the adverts, and they say they will delete it.

Hope that helps