Make a nice polite blog post with all of your documentation (including your sales receipt) and then send the link to him.
This was about two years ago and unfortunately their excuse for service is ostensibly unchanged, rated as 1.33/5 on one of the larger national rating sites (at the time it was 1.4).
I work at a big company and get sales, marketing, press, and customer inquiries ALL THE TIME, at my PERSONAL email address (which is easier to find than my work address). There is absolutely nothing I can do to help you if you contact me directly because company policy forbids it, official channels exist for a reason.
If a company suffers from people contacting the wrong people, I think the solution is to make it easier to contact the right people.
Also, you could just inform the customer to resend the info to the official channel and make sure someone is actually keeping an eye out for it.