Potchefstroom Girls High denies liability for damage to vehicle

I have written a complaint to Potchefstroom Girls High about the damage to my vehicle that occurred at their premises during the marking of matric exam papers in Dec 2024. In their response to my complaint, they said they are not liable for the damage. However, the damage was caused by their irrigation system, which was used at the spot where they instructed us to park our cars. We took the car to three different car wash and valet places, and the water marks were not removable. Eventually, we found a service provider who was able to remove them at a cost of R3220.00. I think it is wrong for them to deny liability for damage that they caused.