It's pretty easy to get in contact with someone most of the time if you search for relevant roles on google with site:linkedin.com, or if you want to reach execs, on their business pages. I usually include several combinations of first and last names @company.com so like I will email to JSmith@company.com and JohnSmith@company.com and others. This is useful for escalating customer service complaints if you're just hitting a brick wall with the low level customer service staff.
They do have a vulnerability policy page, but that was harder to find than figuring out an email address. I did suggest they implement security.txt, as it would have made things easier.