Travelstart and Woodford Car rental

I have a credit card I share with my husband. I was informed that the car cannot be released to me since the credit card was not in my name. I tried to explain that I have a joint account with my husband and thus do not have my own credit card and offered to provide my marriage certificate for record or a signed letter from my husband giving me "permission" to use OUR card. None of these options were accepted by the rental agency which cannot be acceptable, why can companies do car rentals for employees with a letter but my husband cannot do the same for me? I was left stranded at the airport with limitations on business meetings I were able to attend during the week. Since the car was not released to me and thus no services rendered, I requested to be refunded in full. Travelstart refuses to refund me because the credit card doesn't feature my name and this requirement was sent to me before my departure. Great, yes it did. But again how do people with joint accounts then book vehicles, why is my marriage certificate not acceptable proof nor a letter from my husband but companies can book vehicles for employees with a letter? No explanation received on this, just the same automatic response every time.