Underhanded business practice

First you get a call from them to please bring in the vehicle you want to sell so they can evaluate it and make an immediate offer. If you accept the offer they will do an immediate payment. Took the car we want to sell and even though I told them multiple times that I was not the registered owner so I can not sign there paperwork as the owner was told that it doesn't matter. 2hours later after pictures were taken I was told that they will call me later after advertising the vehicle. I got a message around 5pm stating that the vehicle was currently being loaded, 10 minutes later another message for all my details- banking details, vehicle papers, ID copys, proof of residence. I ignored the request as again I can not give my details for a vehicle that is not in my name to sell. Got a call on Monday asking for the details and advised that I will not be going ahead with Get more car due to the way they conduct business. Today got a call from a private person that the staff gave my number to without my consent wanting to buy the vehicle. Your personal details are not safe with this company!!! I asked why my details were given out and was told that he did not know I would get a call.