Towing Excess Fee ridiculous

After being in an accident in a dangerous area, i took the towing company that came to the scene first which was safer for me. I sent all the details of the towing company to my insurance as they wanted to know if it was an approved company on their side. They didn't come back to me until today when they sent me a bill of R6700 for the excess as the company wasn't approved. If I had known I would have moved the car to an approved towing company but they didn't say anything until now. I am so disappointed and refuse to pay that amount. We have never claimed and we have two other cars insured by them for years now. I want the excess to be waivered.