Would Hertz SFO pull a vehicle from this Mason location and add to its "Reserved" line if it didnt have the right class in stock ?

IE:
I have booked (via a 3rd party/Broker) a "FFAR - Full Size SUV" for this Sunday, with return to LAS........
Hertz website doesnt show the option to book a FFAR , so I booked it via "Virgin Holidays".....
Its a full Pre-paid rental, and i have completed the online check-in.

What concerns me is, i dont see any availability at all to rent FFAR (even with return to same Pickup) , and dont see any FFAR at Hertz, or Dollar/Thrifty...........

Makes me wonder if they lack the vehicles, and dont bother to get this sorted in advance, last thing i want after a long flight is to turn up in the afternoon to be told "we got no Full Size SUV's........."