To bypass the responsible disclosure versus full disclosure debate: I provided them with well over six months of time to fix this and reported it last year. My own data is in this set.
Did you try reaching out to Troy Hunt, by chance? In the event of failed response from the site, I would maybe pass breaches to him, as he seems to be fairly successful at getting responses from breached organizations, and has an effective setup for notifying those breached.
Good work, in any case.
I sent this to Krebs and Troy shortly after uploading it.
Whilst that does appear to have had the desired effect in this case, I do hope to never find ourselves into the position where "responsible disclosure" includes "consulted with Troy Hunt" as a step.