No rental car and no refund

I booked a flight and car rental. The flight was fine but when I went to pick up the car they required a credit card and I only had a debit card. And they would not accept my phone's Apple Pay. When I requested a refund for the car there was no way to do that online and no way to contact anyone at Expedia. I disputed the charge with Citi Bank but Expedia refused to reimburse me. Worst support ever. I will cancel my Expedia account, which I've used for over a decade.