ABSOLUTELY RIGHT.
You PAID for leather and fiberglass and you GOT MDF and grill cloth. This is total ******** and I agree that it isn't a good look. It's not HORRIBLE, but it is something any schlub with a router table could have pulled off.
Threaten to go to the BBB and to make it well known to everyone you know (including the vast online forums audience) that they lied and did not make it up to you. What they've done is fraud, pure and simple. A verbal contract is a contract none-the-less, and will hold up in court in many states. They can tell you they "didn't have to" all they want, but unless they're disputing the original agreement, you've got a solid argument.
Worst case, they get their MDF and grill cloth back, and you take your $260 somewhere else to repair your door panels, I'd say.