I'm assuming you're not involved in the tracking of tasks and releases in your job ? Because linking support ticket / customer to a task, and a set of tasks to a release, is a very common and regular feature of task tracking.

I'm not saying it's not awesome that they contacted you and others like that, it's the rare kind of great marketing that benefits both sides, but I certainly do hope that a company working in their field would know to use proper dev tools and not "go back though 3 and a half years of support tickets to find customers".

(I have no idea why there aren't more companies doing it)