We've had something similar happen to us at a consignment place. They wanted our credit card number. They claimed it was to hold the unit for us so it wouldn't be sold before we could get there to see it and drive it. If we didn't like the unit, we would not be held to it.
We declined the unit after seeing it. They wern't supposed to charge our card, but somehow it accidentally got entered and billed. I was pretty pissed! When I complained, our money was refunded. We did not purchase anything from them.