$15k in credit card debt

Looking for advice. I have $15k in credit card debt across 4 cards. My credit is 511. I can’t keep up with the statement balances on the higher debt cards (both $4k). Statement balance was $500 this month on one, and $300 on the other. I’ve paid $300 of it but have nothing left to give to them. smaller cards are no big deal and I pay more than the statement balance and am getting those paid down. Is there a way I can combine both $4k cards? I can’t get a balance transfer card. I wanted to get a loan to pay those off to help my credit. I want to sell my car for $5k to pay a majority of the $8k off. But then we’re down to one vehicle. Would it be worth it? Any advice?