Just so I understand your situation correctly, are you in the U.S. David, and these payments are coming in from Europe? If so, I'd probably give it a little more time if it's only been a couple weeks so far. I've had numerous trading transactions on the boards (mostly domestic though), and sometimes it can take a couple weeks for things to work out just between other members right here in the States. A couple items I've traded for from overseas folks (mostly in Asia) can definitely take a good 2-3 weeks to arrive sometimes.
I know we all like to get paid for our any of our online transactions ASAP of course, but sometimes things just come up, people head out of town, or folks get a little lazy, causing delays of varying lengths... Of course a cutoff in correspondence may be an added concern in your situations here. But when it comes to leaving feedback on eBay, I usually give it almost a month (with a few polite reminders/warnings near the end) before I think about hitting someone with a neg. Especially if they're overseas. So try to hang in there a little longer I suggest.
Good luck!