Lessons to be learned about shipping USPS

I bought a piece of trim from a seller on Facebook Marketplace.

The listing said it ships for 9.25.

I paid the asking price plus the 9.25 plus tax.

When the package arrived, the Post Office dinged me for 15.00 due to the package not being "rectangular". The seller used a triangular shaped priority mail box supplied by the PO.

WHAT A RACKET.

If you tape some cardboard to the outside of the triangular shaped box, it's now rectangular and you save 15.00.

Unfortunately the seller is not being cooperative. So I guess I'm just screwed.

Moral of the story... Only ship in a rectangular box.