USPS Lost expensive package

Hoping to get some advice on an unfortunate situation I am in.

My fiancé ordered some wedding dresses online recently to try on with the plan of purchasing them if she liked them and returning them if she didn’t.

She chose to return both of the dresses company she purchased them from (Azazie) within their seven day return period.

I went to drop them off at the local post office for her on Friday the 10th. The post office was busy, so employees were waking through he line asking for drop offs, and they took my package, no questions asked. They looked at the bar code on the label and said “okay you’re all good.”

What I, and the USPS employee failed to notice is that the label said UPS, rather than USPS..

So the package was actually intended for a UPS drop off, and it hasn’t registered at the USPS, so Azazie reached out letting us know that if they don’t receive the package in a few business days, we’ll be charged for the dresses.

We went to the post office today, and they informed us that they don’t have the box, it might have been sent to UPS, but they can’t do anything for us. When we called UPS, they confirmed they have not received or scanned it yet.

So we’re just waiting in limbo, hoping this box shows up at a UPS carrier facility in the next business day or two.

Does anyone have any advice on this? I feel personally responsible to a small degree, but am largely upset that the USPS didn’t notice the wrong label immediately and tell me where to take the package. Nor did they send the package to the return address when they noticed the incorrect label..

I feel the USPS is liable for losing this very expensive package.