Damaged my vehicle

They damaged my sump cross threaded the female end on the sump and only to find out now when i am doing the next service at another dealership for this i need to cover the costs for repairs. i complained to Barons Kuruman, their service manager wants me to provide them with proof that they they where the ones who actually damaged the sump ? I asked for suggestions or what proof was required in order for it to be a clear indication that it was their fault the service manager response was " i dont know you tell me ? " And also stated that they are not going to pay for everyone's cars .... So i presume that poor workmanship related issues occurs quite frequently at this dealership ... Truly Pethetic.... Here's the kicker my car has 145000km so he claims that due to the fact that it has been serviced approximately 6 times its normal to expect that the sump will get damaged to this extent .... Utterly amazing that a VW sump lasts between 6 to 7 services.

Will not recommend that anyone takes their vehicle to this dealership for any maintenance