Courtesy Car

It doesn't make sense to book for courtesy car 2 weeks in advance as the consultant informed me today. How am I supposed to know the nature of the repair and if the car is driver able, why they don't give me back the car and schedule the repair in two weeks so that they give me courtesy car, when I leave them with the car. And when you call they don't answer. Now I don't know how long I am going to be without a car as they send the radio for repair. How m i suppose to get to work. When i buy a bmw i thouht I will have relaibility and a piece of mind, but now i have to take taxi because the radio has to be sent away for repair and i did not book 2 weeks in advance for courtesy car. #Bad service. My registration CR97TS GP