Send a high priority email to their customer support (or alike), wait 24 hours, if no response is received then tell the customers (blog post? forum thread? hne

Send a high priority email to their customer support (or alike), wait 24 hours, if no response is received then tell the customers (blog post? forum thread? hnews/reddit?). If response is received wait a week or so and, again, check for the existence of the exploit.