Frustrated Customer

I bought a Renault Duster on finance, went to fetch it and everything seemed to be alright but fuel was empty and I was told they poured R200 so should I pour more the gauge will pickup, so I did and discovered that the gauge wasn't working. Same day (Friday evening) I let the salesman know and he promised to lodge complain on Monday. Saturday I realized that the right rear door was not in sync with the central lock and I reported that also. Monday he told me that I'll receive a call which I never did until a week and a half later when I called the manager and he said I should bring vehicle in for assessment and I did so two days later. They asked I should leave my car and fetch it following day if I can't wait 3 hrs for the fix so I left it. Next day I had to call both manager and salesman continuously to get response on progress until after 4pm when they eventually said it'll be ready next day at 12pm. Next day, the salesman this time communicated properly and gave me updates and just a few min past 12 he called me to say my car is ready, I can come fetch it. So later after work I went there but to my surprise only the central lock was fixed but gauge still not fixed though manager claims that it worked. Don't you test that all defects are resolved before calling back client???? Now I have to wait again for them to tell me when I can bring it back to fix the gauge. I'm frustrated because it seems my issues are not taken seriously and it's difficult to have a prompt response to complaints. The service I'm experiencing thus far is poor for such a big company.