Worst car repair experiance

I have had the worst experience with renew it Greenstone. I had an accident on the 28th April and my insurance handed my car over to them for repairs. they have had my car ever since beginning of May and i was told that repairs will commence once all parts have been received and that repairs will take 10-20 working days. Parts were received on the 3rd June and i was promised multiple times that i will have my car within the 10-20 working day period which was fine with me. Through the entire process they were not sending any notifications or updates, I had to constantly call to ask for progress and only after i have made the call will they send an sms. I had to follow up the entire 2 months and now a day before their 20 working days period expires they are telling me that the car is not complete. I call them and they keep saying they will forward me to speak to the manager or they will contact me back with proper feedback, no one has called to provide a proper explanation and i have a trip planned for the coming weekend and without my car my plans are ruined with no one willing to give me an explanation as to what caused the delay and if they are working on a solution.