Buffalo Technology Buffalo drives Won't honor warranty for defective unit. Won't take PayPal receipt. Austin, Texas

Buffalo Technology will NOT accept my PayPal receipt as proof of
purchase of my NAS Drive.
Purchased a Buffalo Link Station Pro, Dual-Drive Shared Storage Unit, 2
terabyte, on April 17, 2012 from an ad on eBay. It was advertised as
"New" by the seller. I submitted my receipt to Buffalo when the unit
failed (one hard drive failed out of two). They sent me an email back
saying that they would not accept a PayPal receipt as proof of purchase.
It is my receipt, my original receipt. The serial number on the failed
drive shows that the drive is still under warranty with Western Digital,
who manufactured the drive, however, they will not replace or repair
the drive under warranty because it was sold as an "OEM" drive to
Buffalo.
Buffalo's warranty statement does not state that PayPal receipts are not
acceptable. If so, it should be stated and I should have been informed.
I bought a new product, in good faith, that the Buffalo Technology
company would stand behind their product and warranty. I am sure they
have a warranty agreement with Western Digital who makes the drives. Now
it is time for them to stand behind their product and customers.

My Desired Resolution:
Replace the defective drive, Western Digital drive #WD10EARS, serial#
WCAV5P074731, with a new or refurbished drive and to return the $270.00
they charged my account for return safety.
They charged me this before even checking my receipt for eligibility.