A good customer is standing in your office complaining that the dealer has refused warrenty because of the non-dealer parts you fitted. This is after you have explained block exemption and talked them into allowing you do the service.
The parts you fitted are of equal quality to the dealer one's, maybe even made by the same company. You have done nothing wrong, but you still have a problem, an irate customer.
To sort this, you have to make a trip to the dealer and fight for your customers rights. All in all, you lose out in time wasted for the sake of a few quid extra on the parts margin. This is of course if they were not cheaper at the dealer, which they often are.
Not me thanks, I will stick with dealer parts for anything thats under warrenty.