Who Pays when Post Office is at fault?

[PBOR]

I purchased some textbooks in April and haven't received them. I contacted the seller, and I know she shipped them. She provided a tracking number, and I can see it did ship when she said. The post office tracking shows the package as "Dead" and "Undeliverable" and it stopped somewhere in Seattle, WA. I have contacted the post office and was told the box may have fallen apart and contents were lost or misplaced apart from the address. They just told me to fill out a form. I filled out the very detailed form complete with stock photos of the textbooks and ISBN numbers. I haven't heard anything in 2 weeks except from my local post office, who says there's nothing they can do and they don't have any contact numbers for the holding warehouse in Seattle. I'm not sure what to do now. I paid for an item I never received, but it was the fault of the post office not the seller, so what happens? Do PayPal fees help or will the seller be out all the money if I file a claim?

[kernowlass]

@PBOR 

You pay a seller to get the items to you in the condition that you bought them.

Any good seller would have refunded you by now.

The seller refunds and then claims from any insurance they took out when they sent the item, if they chose not to do so then thats their risk to take and not yours.

If you bought from Amazon and it didn't arrive would you want money back from Amazon or just say 'never mind' post offices fault?

If i was you i would be filing a dispute for non receipt of item via the resolution centre.