Dealership Service Centre cannot fix my vehicle

I have a Hyundai H1 Wagon (CY219 260) which has been at the service centre for the past three weeks and still I dont get an answer on what the fault on my vehicle is. I am stuck without transport and the dealership do not want to provide me with a courtesy car whilst they try and fix my vehicle. Every time I call and ask for an update, the answer is we are busy with it but they still need one more day. One more day has no become three weeks!!!. This is really bad service from Hyundai.