There is a significant difference in the diagnostics between the aftermarket and the factory due in part to the diagnostic equipment being utilized. Unless the independent repair center possesses an SDS/DAS system tester a complete system diagnosis on any late model MB, at best will be extremely challenging. A dealer technician may have 300 pieces of information that are accessible/viewable with the SDS/DAS for that system. An aftermarket scan tool may only provide a fraction of that information, say 100. Without access to the other 200 pieces of data how effective will the diagnosis be???

I am going to go out on a limb and speculate that the core issue is "someone is going to pay for the pump?" Can all the damage be attributed to one event? If so, which event? I do not believe I can provide you with the reassurance that crossing two lines to a single cylinder caused the pump to fail.

I am unable to connect those dots ……………..the way I see it, the cylinder would simply work in reverse.