It's been 10 days since then, and I still haven't heard anything.

What next? Anything? Or do I just eat my credit and move on?

That would suck since I was planning on making this a keeper and I've already reordered it from someone else to get a better copy.

When you PMd the sender, did you hear back from them?  If not, what you should do is send in feedback about the situation through the "contact us" link below.  I am not entirely sure that PBS reviews all the transactions that are "unresolved" but I do know that they respond to emails within a few days.

ETA:  If the sender DID respond but is just refusing to return your credit, I wouldn't send in feedback.  Unfortunately, in that instance, you just have to eat the credit.  :(

Thanks!

Chris it is against the rules to ignore you if you ask for a response. PBS asks that you wait 1 week for a response and then let the site know that the person is ignoring your PMs. Since you have waited 10 days, you have passed that time and can contact them now.  It is a double black mark on their account if they do not communicate. If you haven't PMed them lately, maybe send one more note stating that if you do not hear from them by X time you will be contacting the site leaders and that will give them the double black mark against their account.