Diff oil bungle

A CHATTERING noise has developed in the rear of my 2001 Holden Statesman Gen III V8 -- most likely coming from the limited-slip diff that was fitted as an option. The car has been serviced regularly at a Holden dealership and apparently during the 80,000km service ordinary diff lubricant was put in instead of the high-performance lubricant. What damage can occur through this action and should I expect any compensation from the dealer?