no service giving

Went at branch witbank on 28april with my car that has a problem, after many attempts done and check the mechanic said it is the sensor that needs to be replaced after he said that car is fine I told him the car only idle up down up down while I'm driving not standing still, he said that he will order that sensor, I asked him when it will be there he told me on monday - today but when I called them and asked about it, no one knows about it and it was never been ordered, they did not even took my details or nothing at first when I was there, I feel that is really bad service my car is not light on fuel because of that faulty sensor that make my car idle like that, and now I must wait again and if something happens while I'm waiting and use moore petrol? I do not even have a price on it and what else it will cost, I also have a motor plan but ya that people does not know what is going on at their branch and it is pefectic