@RandolphY504124
That sounds really crazy. Sometimes a price may increase since these are so dynamic. But to change so greatly? and twice in quick succession? Some fluke of some sort. And to have this presented to you when you are paying? Doesn't sound right.
I generally purchase air travel, hotels, and rental cars separately, generally at each company's own site. I shop around using Google Flights for air, then Expedia, etc, for hotels and rentals (though I prefer Enterprise and will use them if the rates are competitive) but then go to the company's site to reserve/purchase.
Expedia itself owns Travelocity and several other travel websites! Including www.carrentals.com (but not, to my knowledge, www.rentalcars.com, nor www.carrental.com).
I use my American Express credit card for as much as I can (even shopping for groceries and gas) but I haven't found their travel site to be of any greater utility or pricing than just shopping around ala' carte.
There are so many "problems" with purchasing travel arrangements, some outright scams, some just too much friction ($$) due to middlemen (and middlewomen), that one really has to be a wise, informed consumer and not simply accept that "ol' so-and-so" is a reputable company or interest group and I'll trust them (but you can't as their travel services are likely passed out to someone else...who may not be so reputable or interested in your welfare).