Adding Gold Rewards# to a Booking.com reservation?
 

Hi,
I did some searching in the archives here but nothing specifically to do with my scenario popped up. I've made a car rental booking through Booking.com (well CarRental.com specifically but they're owned by Booking.com) and there was no place to add any kind of loyalty details during the booking. Non of the confirmation numbers they've provided pull up a reservation at Hertz.com so I'm stumped how to add my Gold Plus details. I'd ideally like to attach them in the hopes of an upgrade beforehand but not the end of the world if I can't. I contacted Booking.com and they said to contact Hertz directly but I'm confused if their website isn't finding any booking for me based on the various reservation codes (for some reason Booking.com provides about 5 various confirmation codes!)
Thanks in advance,
FD

Thanks TerryK but it doesn't seem to address the specific question r.e booking with an aggregator (i.e Booking.com) and not recognising the booking...I'll keep trying!