I'm bought a Renault by planet42 and Black Stone Assistance but the consultant come with the owner of this car late this day and is a hurry and said I must sign the papers

I'm bought a Renault by planet42 and Black Stone Assistance but the consultant come with the owner of this car late this day and is a hurry and said I must sign the papers. I signed it but the other day I inspected the car and there was so many problems and nobody can assist me with no contact number. All I want to know it's that how you doing business. This car is in a very bad condition. And I wanna cancel the deal with emmidiate effect and I inform the owner of the car but the car is at my home and you must send someone to to fetch it