I remember an TV-article about the Chaos Computer Club (CCC), which you probably know from somewhere and despite their name are not about spreading chaos, but a productive hacking-community, that tries to help mankind with computer-security-related issues.
The interviewed guy said that one of the reasons of the existence was that if someone found a security issue which is related to hacking (in a closer or further relationship) can come to the CCC and discuss it with them and so they again can contact the company with the security issue. The benefit of this is that the CCC as third 'person' can not be sued for hacking (no matter if he didn't want harm anyone). I am not sure if I am getting this straight the way he said it, but something in that way.
So maybe contacting them might help you. For a start you don't have to tell them the way you did it, but ask them for general advice.