Making a mess of a relatively small and simple fender bender

I have had my car at dube for about a month now and I have had issues from the 1st week when I was emailed authorization by Miway and when I informed them by giving a print out with all relevant claim numbers, I was told that they were waiting for Miway to email them directly, two day's later I get a call from dube that they haven't started working on my car was they are still waiting for the authorization, I then asked why they are not calling miway to clear this up and I further highlighted to them that on the email I received miway still had their old email address, so logic would have me think they should have called the same day I delivered them the authorization. So two weeks later I'm calling to get a date of when my car will be ready as I have a weeks holiday booked and need my suv. I'm told they can't give me a date, to which I reply, "are there any parts outstanding or is there any other hold up?". I'm told that no but the panel beater is still busy with it. A week later I decided to pay them a visit, I find my car outstanding in the rain with the electronic key's on the windscreen soaking wet and the grill and other small plastic bits missing. I'm then told that there are more parts that they only found out now that they need and they still need to contact insurance to get authorization for these extra things. At this point I'm feeling totally defeated and I'm lost for words at I don't want to loose my temper and say harsh things to the lady, so I ask to speak to someone more senior. I'm referred to their internal assessor who tells me that they will try pre order the outstanding parts while they waiting for authorization. I don't how such a seemingly professional looking company can be so *********** at something they do for a living, their soul responsibility. I'm due to leave for my 4000km holiday in a day's time and I don't even know if I will have a car to start off with.