Disputing damage they did on the vehicle

I booked my vehicle in because I had a burglary in my house and the car keys were ******. I only had one key, so they had to replace the key. Car was uplifted to Mercurius Motors Polokwane on the 4th of October 2017. An inspection was done and I was provided with the checklist of the mechanical problems the vehicle had.

When I collected the vehicle, I noticed that there was a warning light which was on. When they diagnosed the vehicle, report stated that it is the "steering wheel sensor".

That problem was not on the checklist which they did when they received the car meaning that the problem came after. But the dealership is disputing that it is their fault. If only they can provide me with proof to show that the "steering wheel sensor" was faulty when they received the vehicle.