If you want to go hardball, you could leave a message saying that if you do not hear back from them in X number of days you'll file a complaint with The Better Business Bureau Online.

They may not care, but then again you never know. Before I order online I check to see if the company is registered with the BBB (usually they have a BBB graphic link) and then I check to see if any complaints have been registered against a company at BBB Online..

Sometimes you get nothing there, but other times you can find information on the company you're checking out.

Anyway, if they're interested in keeping a good name, then the threat of a report might prompt them to contact you in a more timely fashion.