ebay question for sellers

[tonyo]

Hi all,

Here's are two "what would you do ?" questions for sellers.

I sold a $30 card on ebay 12/30/18
Received payment on 01/01/19
package dropped at P.O. 01/02/19
First scanned on 01/03/19
last update to the USPS tracking number was 01/07/19 (In transit to next facility)
Buyer opened a case on 01/11/19; he checked "haven't received item" his comment was "what's going on here? no progress on tracking number since 1/7"
I responded politely including this one:

I mailed quite a few packages on that same day (12 to 15). Most have been delivered, but there are still three including yours that say "in-transit" since 01-07, and a 4th that said "in-transit" since 01-06, and finally arrived at the next post office on 01-11. Still not delivered, but I expect it to be soon. So, hopefully it's just a matter of time for the other three. Thanks for your patience! I've been on your end many many times - I know it's frustrating. Enjoy your saturday!

We traded a couple of reasonable messages. He hasn't demanded a refund yet.

As of today 01/17/19, still no updates to tracking. Of the four I mentioned that were "in-transit" quite a while, his is the only one that hasn't re-surfaced.

My questions for you are:

first, what is a reasonable amount of time to allow a package to "shake loose " and resume it's path to the recipient? (I'm thinking One month on this $30 card)

second, what do you do if you issue the refund, then later see that the USPS finally delivered the package, and the purchaser doesn't offer to "pay again"? (I'm thinking I'm at his mercy at that point, and have no real recourse)

I suspect this situation isn't uncommon, curious how you handled?
thanks in advance for any opinions!