One other small point which may be worth mentioning. All my correspondence to customer services of any note was copied to this place. Its always worth letting them know you are a member on here in my opinion.
They are well aware of this place and its not a matter of threatening to slate them in public, more a suggestion that you are well aware of other people with issues which seem to be related.
I would definately let the dealer know that you are not happy, Nissan CS will have contacted them anyway. The next move should be you getting bumped up to a senior manager.
They will also be very keen close the case when it has been resolved, leave it a while until you are sure all is well.