Colo Customer Unreachable And Past Due

In short, we've tried for months to contact a client and he's basically fallen off the face of the earth. Emails were originally received by his mail server, but now they bounce. His phone used to ring and we could leave voicemails, but now it goes straight to voice mail. I have a weird hunch he passed away or went to prison or something. We haven't heard from him in about 45 days.

He has pretty expensive hardware that any reasonable person would want back, but it's eating up a lot of space on the rack considering it's unpaid for.

So here's my question to other providers: When a colocation customer is completely unreachable (phone, email, etc) and way past due, what do you do with their hardware?

And customers: what would you want done with your hardware?