SBIS does not care about its policy holders!!

I would like to complain about the frankly pathetic service I have received from SBIS. My car was in a really minor accident on 20th August - drove over a pothole - and the differential needs to be replaced. After THREE weeks of waiting for an assessment, my claim was approved. Now after a week of the claim being approved with I am still waiting for my car to be fixed. The car is at Auto Atlantic in Cape Town who have declined to replace the part as SBIS is reserving their right to exercise the clause in their policy that says that they have the right to put on a second hand part which I have been told that comes from another car that has been written off. I must add that I do not pay a small premium. My premium is approximately R2900 per month. I did not get the chance to even choose the new part over the second hand part from a written off car. I haven't received any excess quote now have I been given any date for my car to be fixed. So one month later, after driving over a pothole, I still do not have a car!! My emails are being ignored and my car has not even been moved to the new workshop to fit the part from a written off car. I have requested also to know what the guarantee on this part and work is - but no reply. I really would like anyone out there to advise me on what to do further. My appeals fall on deaf ears. All I can say if anyone is thinking about this insurance company. Buyer Beware!!