Flysafair damage checked luggage, but not paying for repair

On a recent domestic flight from CPT to JHB, I booked and paid for sports equipment (a surfboard) to be checked in. When I arrived back in CPT I saw that my surfboard was damaged and was in need of repair. Flysafair informed that I had to claim directly from their insurer. After contacting their insurer I was informed that I require an incident report from the airline. It took months, many emails and at least four phones calls to get this from Flysafair. I was then told that the amount I'm claiming for the repair was less than the excess I would have to pay. I have since asked the airline to pay for the damage they caused to my sport equipment that I paid extra for them to transport and have not received feedback after many emails and time.