Unhappy Paying Customer

My problem with the radio and the hooter started beginning of August, I took my car (Datsun Go+ 2019 model) in to the dealership and booked it for repairs. I was assisted by the lady called Lindsie. She arranged that the radio get fixed and ordered a new hooter. I drove around without the radio and hooter for over 3 weeks and then she called me to come in to put back the radio as she has a new one waiting for me. When I got there the radio was connected to my car however it wasn't a new radio (as per her words) but my old one which was fixed. Lindsie then called me again towards towards end of September to come and collect the hooter, the radio has already stopped playing again by that time so I went to the dealership on the 25th of September to change the hooter. I then told her that the radio is no longer playing, she advised that she will get it fixed and that was the last time I spoke to her. I then decided to let the head office ( Nissan SA) know about this bad service I've experienced by rating the dealership bad on their survey. I received a call from Cindy ( the dealership manager) and she promised to get the issue sorted out, but never did. However since the complaint was logged at the head office, the lady by the name of Carin Dreyer handled the complaint she kept on calling to find out if the matter was resolved. Eventually a technician came last week Thursday to fix the radio again. The radio played one day, Friday only then I was back to square one, that technician promised that he has got rid of the problem. But the problem is still there. I'm very furious about this because I bought the new model because of the upgrade that was done in it which includes this radio that is giving me problems. What I would like know is that is this how they treat their customers? How long should I wait for them to change this radio because it's obvious that it cannot be fixed!!!!!!!