The category that the OP booked was not one with reserve exact model, so doesn't apply
if there is only 1 vehicle type in a category, it seems quite reasonable to offer to reserve that exact model

The issue that the OP faced is that
(a) there was no vehicle of the category booked and
(b) that the location representative stated that the location doesn't even have that category normally

If there was no chance that the vehicle category would be available, then that category should never have been available to rent ( exact model or not)