Our current communication is focused on getting the hard facts out to our merchants - we want to be transparent and clear about what is happening and what expectations our merchants should have around this service outage. It's slow going, careful work with many moving pieces, so our intention is not to be uncommunicative, but to provide details as we have them.
I invite you to contact email@example.com if you have any questions - I will handle all inquiries personally. We are committed to making this right and helping our merchants in any way possible.
Good luck! This has to be tough (I've seen a fair number of HSM and key management related failures; sucks how security and reliability are sometimes at odds...)
Please put a full postmortem on the Internet (and ideally describe what hardware went wrong AND how you'll prevent it in the future) once you've finished immediate recovery. I'd suggest it come from VP Eng, CEO, or Founder level people.
If you can make a credible case for why this won't recur, it shouldn't have a long-term negative effect on the business. (A vendor who had a problem and learned from it is often safer than a vendor who had no problems and has just bene lucky...)