Help with car finance

[Kjoaldr88]

I was struggling to get car finance so my sister agreed to finance a car in her name 4 me ans id just pay the monthly amount. She has the logbook in her name and I drive the vehicle and pay the finance. after a falling out she decided she didn't want this anymore and asked the finance company to transfer the car to my name which they won't do. She stopped me paying the monthly payment to her so nothing was paid. I contacted the car finance company and asked them to collect the vehicle and voluntarily terminate the agreement and set up a payment plan to pay off any money owed. They have now sent me a new purchaser questionnaire asking how much I paid for the vehicle and when I bought it. But my sister hasn't sold it to me and the log book is still in her name so I don't know what to do. I don't want her to get In to trouble for helping me out when I needed it and this document seems formal. I just want to reply to say I cannot fill it in as I haven't purchased the vehicle and I am not the owner. I just want the car to be collected can anyone advise? Is what we did illegal? Thank you