Incompetency, running the workshop not properly

On Friday morning i booked in my car for major service and in the evening when i came to fetch it i was told that among the parts they replaced the new alternator is faulty and could not charge. And they told me they cannot do anything i will have to come back Saturday so they send it back to the supply the following morning. Saturday morning as i was on my way to fetch the car they told me they cannot get the alternator and therefore come back monday afternoon. I told them i cannot come monday afternoon i need the car have to travel for holidays. We arranged i buy the alternator and bring it, which i did but when i arrived the workshop was closed before time and thier phone off and had to travel back home. No communication and they showed so much incompetency..