Charged twice & decline to refund for their mistake

Charged twice and won't refund. Misleading information online first about the type of the car, after I called to cancel the reservation because the car type wasn't available I was advised to make another booking and write to customer support for the refund of the first booking, what I did and got a rejection. I was charged twice for hiring a car and I was rejected a refund. Their reply was: "The car you were offered (Peugeot 308) is in the same car category as the Fiat 500X.
We never guarantee the make or model of the car online, this is why it always says "or similar". Therefore this booking was walked away from while it was still offered to you. In this instance there will be no refund for the booking." I appreciate that the car should be similar, but the company providing the car said that they believe it's a different category and they never had Fiat500X in stock at all. I called back to cancel or to change the booking, I was offered to make a second booking and to write to the customer service for refund. Awful company made me a loss of £100 and lots of time on the phone and with customer services. Should be ashamed being in the group of "easy".