I am a customer of an international company whose logo is highly recognizable and whose brick-and-mortar services I use frequently. I pay for these services by credit/debit card on their website. I noticed two months ago that the website has a vulnerability that exposes credit card numbers through form field caching, which means that public-access computers could expose credit card numbers (and security codes) to others.
I have contacted the company three times in the past six weeks. Their website makes it impossible to know who their security people are or which continent they work on (this is a company that has presence in over 100 countries). I have written the press office three times. None of my communications have read by a human, as far as I can tell.
I will be giving them another week or two before I go public. I’ve told them so in every way that they make available. After telling them almost two months ago, I logged on today and the vulnerability is still there. It is SO easy to fix – it does not require any changes to their data model, workflow, or processes. All they have to do is add an ‘AUTOCOMPLETE = “off” ‘ to two fields in one form and they’re done.
As a security professional I am duty-bound to inform this organization. I’ve done so many times, and have not heard any response. If they continue to turn a deaf ear, I will go public in April.
Peter H. Gregory 
Update: I won’t be going public just yet. I have received some excellent guidance from some colleagues. Stay tuned.
Update: I’ve made contact with the executive who is responsible for corporate wide security and risk management and disclosed the vulnerability to this person. This should help to close the vulnerability and protect users.
Update: the company closed the vulnerability two weeks ago.