Looking for advice ...

A company in Austin, TX agreed to purchase a domain name of mine by FAX'ing an Acceptance Letter in response to my Offer to Sell Letter to them dated April 12th. The opening paragraph of their Acceptance Letter response reads as follows:

Pursuant to your offer dated April 12th, 2004 please allow this FAX to serve as acceptance of your offer. Once countersigned by you and faxed back to ###-###-#### will create a binding agreement to the terms and conditions outlined herein:

And the balance of the letter stated the domain name, price, etc with a closing date for deposit of their funds into Escrow.com no later than April 22, 2004.

I indeed FAX'd it backed signed, but thus far the deal has not been closed. Tracking them down via phone and/or Email for an answer has been tough ... they claim that their client is the one dragging his feet.

So, any advice on my options? The agreed-to amount exceeds $10K.

Thanks!