Someone I know tends to email the CEO in situations like this, with a surprising level of success. They usually have a team of people managing their inbox. In several cases he’s ended up with a dedicated point of contact to see things through to resolution.

No shibboleet[1] i'm afraid, the best you can do is raise the storm.

[1]https://xkcd.com/806/

[flagged]

have you tried a handwritten letter?

People tend to answer the contact form and either call you or send email before they answer the phone. This is also true of email.