Have guests already paid Booking.con for smart flex reservations?

Hi. For the third time this month we have had to argue with a guest that they have not already paid for their reservation. These all turned out to be B.con's new 'Smart-flex' reservations which see us get given a virtual card to cover the cancellation period and then incomplete guest card details (no CVV).  For some reason, all these guests think they have already paid and in one case we had to charge the Virtual card as they simply refused to hand over any form of payment at the end of their stay.

So, have they already technically paid B.con?  And if not, why do they all think that they have? Is there a problem in the pre-sales process that anyone else has noticed or have we just been unlucky?

Thanks in advance for your thoughts.

UF