Disgusted with Volkswagen Lenasia

Very disappointed and disgusted with the service I received from Volkswagen Lenasia. I took my car in for a small "fix up" in December. I was told it will take a day to do it. It took 3 days for them to actually repair my car. Then I was told the company has a campaign running where they are fixing the airbags. When I got my car back after this, my mirror adjusting knob on the door was broken. I contacted the dealership and they kept giving me excuses and said they will call me back. Eventually they did after speaking to the service manager. I was told they will fix the knob at no cost but I have to buy the knob myself. The audacity of them. I refused flat out because I did not break the knob so why should I pay for it. It is now 3 months later and I still have not gotten a response from them