bad service

After taking the car for service they said they could not fix a few issues I reported prior the service, so I decided to book my car in before going on holiday for 10 days. I left the car at Cape Town Paarden Island on Friday 12 Jan in the afternoon, On Tuesday 16 Jan I recieved a call from the service lady saying that the issue was sorted and that all the elctrical problems were related to the battery whcih they had changed. On 23 Jan I went to collect my car and the batery was flat again, which was strange as they had put in a new battery, after jump starting the car all the issues I have reported were not fixed and one one could give an answer. 24 Jan I called several times and finally got hold of the lady that helped me and now the issue was one of the things I had reported to check, which makes me think that for 12 days the car was there standing and no one even looked onto the things were supposed to be checked. Now they are telling me I need to wait 3 working days for the authorization of the part that needs to be changed. I work as sales rep for a compnay and my car is an essential part of what I do everyday. How can I sort this out.