Poor Service

I would like to formally complain about the poor service received from my insurance. policy number (SASBO81029/11) I took my car for repairs at one of the insurance approved panelbeaters and upon collecting the vehicle I noticed that my right hand side mirror was missing. I informed the insurance and they extended the rental vehicle which is about a week. today I was advised by the rental department that I have exceeded the vehicle rental days and that I will be liable for any additional days the vehicle is not returned. The issue has to date not been resolved by the insurance and panelbeaters and I will be left without a mode of transport. This will result in me not getting to and from work. I need to inform you that I am seriously being inconvenienced and I am not getting any positive answers from the insurer