I recently bought a Chilli Red 350z to break. It's a 35,000 GT UK 54reg car and was loved by the past owner. Anyway he purchased it from a Nissan Main Stealer for a decent sum of cash and after 3 months of driving he heard a bang and all power went off causing loss off power steering / servo assisted brakes etc. The poor guy was coming off a motorway junction at speed so it was a choice of the lamppost or the cars in front! The lamppost won / lost!
There was something not quite right here. The previous owner lived on the Nissan garages test route and they saw the car on his drive and without any contact with the owner they tried to have the car collected on a low loader 4 times! They obviously knew there was some sort of problem with the car as they had it on the books for a year with no takers.
On investigation the main fused link on the battery terminal had blown due to a major fault in the body control module. The Nisan garage must have been clearing fault codes and fuses a lot.
I think an independent specialist is always better than a dealer as it's purely about the numbers with them.
Rant over