Is this one of those account where the person doesn't take Credit Cards and you paid with a CC?

Why else would a payment be pending?

eBay sends a note to the seller. They have a week (or something) to accept. Then they send the seller a second notice.

If it's not accepted, you don't get charged.

But, in order to accept it the seller has to change to a premier account, so you might as well just cancel the payment now and try contacing the seller.

If they aren't responding to emails, I'd wonder why?