GM SA damaged my vehicle while they were servicing it not the don't want to give me a loan vehicle while they repair it

I took my vehicle for repairs on February 2018 and the vehicle came back with a dent. We check ed the inspection sheet with GM employees and came to agree that the damage was not there before. GM agreed to repair the car but would not give not give me a loan vehicle. They are saying that they are repairing the out of goodwill regardless weather they damaged it or not. This is a middle fingure shown to me as a customer after thinking that I left my car in good hand. The dealer principal said even if they had cars available they will still not give me a loan car while the car is being fixed whereas GMSA damaged my vehicle. The customers service has not been anyhelp till thus far. It is more than 5months already. Let alone that the car was not properly fixed after sending it a couple of times back for rework.