Hyundai Bedfordview Workshop doesn't want to admit failure

I took my car there, it has been a month, a month of incurring hefty uber costs. They gave a wrong diagnosis, claimed from warranty company, I waited almost a month for the part. When if finally arrives turns out it is a wrong diagnosis, car is still giving same problem. Now they are keeping my car there indefinitely and not giving me any report. The workshop manager is ducking and diving avoiding my calls. They are refusing to take it to another dealer at their cost, whose fault is it that they hire inadequate technicians?