Bad Customer Service

I bought a Renault Duster (pre-owned) in May 2019 at BB Hatfield. Upon driving it I discovered that something was wrong with the gearbox. I told the sales consulted and was told to bring it in for service. I took it in on the 1st week of June and was given a courtesy car. Until now nearly 3 months later, still waiting for the gearbox from France. In Mid-July I was informed that they delivered the wrong gearbox. I am even thinking of returning the car and cancelling this deal. I cannot be paying for a car that I am not even driving. Their service is bad if I don`t follow up they don't even bother updating me.