It will be interesting if you can pass along a nice description of what exactly the fitment issue is. Too narrow, too short, wrong pattern, etc.
I will say that I also had an uncommon experience on my first rear seat PUI covers I ordered, the pleats were a different width IIRC. They fit - they just looked wrong! Fortunately, the vendor looked at my pictures and was able to recognize that I had been shipped a very old set that was from a manufacturer's bad run of the product. They took them back and sent me correct ones. Granted, your situation sounds potentially more dire. Good Luck though!