Shifting of Blame by Nandos Fordsburg

At 13:05 PM on the 16 June 2015 I was driving in Brixton Johannesburg on Collings street which is a one way and the guy riding a motorbike (Delivery guy for Nandos Fordsburg) who is a Burundi International who was on his way to deliver food to one of their Nandos customers was coming on from Esher street and ignored the stop sign and drove straight to my brandnew Audi A3 which I bought on the 1st June 2015 and he damaged it.I phoned Brixton police station as well as the Ambulance.The police were at the scene ten minutes later and the ambulance also arrived and took this Nandos delivery guy by the name of Jean Claude Bimenyimana to Helen Joseph Hospital and he was admitted as he injured his leg when he collided with my car.I then opened the case at Brixton police station.On Wednesday I phoned Nandos Head Office and spoke to Uriel Sonny and received this Refference number:66742 I then received a call from Mr Jawad Nandos Fordsburg Branch Manager who said that they are not responsible as Nandos, as the delivery guy works for their subcontracted company which does their deliveries.All I want is for Nandos to cover my excess for my car insurance which is R5900 Can anyone help.