What are my options if I put my name on a loan for a car for a friend but the person isn't making the payments?

I have found myself in a really bad bind with an exfriend. Prior to our friendship deterioration, I put my name on an auto loan for the friend. On the registration, the friend used her name instead of mine although the loan is in my name. Fast forward to present day, she is not making ANY payments because she doesn't feel she needs to. So she's driving the car around FOR FREE while I am paying for the loan every month because i don't want to mess up my credit. Problem is I can't get the car back from this person. She is pretty much dodging me. I know I am on the hook for the loan but how do i go about actually getting the car if the person agreed to pay the loan? Civil court? I would do a voluntary repossession but Santander (the bank) says I have to have the car in my possession which doesn't make sense. What can I do at this point? Thank you.