Ethics

I have a client that I designed a site for that was referred by one of my main clients. I invoiced the site 90+ days ago and haven’t received a penny! I only released the site without payment as a favor to my main client. I bill weekly and call every few weeks. I am very courteous and patient. I get every excuse in the book. They don’t answer the phone or return my calls now.

My question is this:
I still have access to there servers… should I take the site back?