Trip.com Double Charged Me With Thrifty for My San Diego Car Rental

Dear Sir, I rented a car from Thrifty.com car rental company through Trip.com with the reservation number of 1638312966907488 for five days, with pick-up in San Diego, between August 5th and 10th. I paid Trip.com $247 in advance. When I arrived in San Diego, they told me they did not have the similar car I rented, that they would replace me with a higher versioned model, and that they would cover the difference on paid price. After all they billed me $292 for this. In addition to the difference and taxes, the invoice included the initial charge. So, I was charged twice. My credit card was charged totally $539, $247 by Trip.com and $292 by Thrifty.com. I opened case on Trip.com customer service. I had extensive evidence, and I presented it all individually. I requested a refund. Despite this, they took no action and simply ignored me making two payments. Trip.com's attitude towards customers was extremely unpleasant. I demand my rights. I want my money back. Best Regards Sinan Y*** Y***