My name is being dragged on the mad and feel threatened by the credit berue people

I have problems with people from nestar , they took my name to credit berue because of their unfinished job that was done on my car and they want me to pay them their money. I don't have their contacts and instead they did not do proper job in my car and I don't even know how their tracker operates, they did not even leave the contact details but they want to be paid monthly.