Advice needed on financing a car

I did ask their customer service to explain why I was being charged such a high rate, and they couldn’t tell me anything. My best guess is greed? But I have no idea. So that’s why I just want to quickly refinance it before the payments start coming due - either refinancing through my credit union or just paying it off in full by taking out a personal loan. Either way will end up being cheaper than paying the Carvana 20%.

It’s gently used and it was a really good price. That’s why we jumped on it, despite the 20% APR offered - we didn’t want to lose the deal, and I figured I could find a way to refinance my way to a better rate after the purchase.