I purchased a large quantity of knobs and handles ...

I purchased a large quantity of knobs and handles from mynobs.com.
They did not work out so I got the return authorization code and return them. They asked I send them directly back to the manufacturer which I did, they also accidentally include the RA number and clearly on the box which I also did. I have sent them priority mail and tracked them and they've been delivered to Atlas hardware how are they cannot prove that they have them and will not issue a credit even though I have proof of delivery