Most Nissan garages should be sympathetic regarding your issues, especially if you bought the car from them.
However all will depend on your relationship with them. how long you have had the car and if they appreciate your business.
Keep your conversations with them low keyed and civilised starting with the guy on reception, moving onto the service manager if you have to and finally the the dealer principle if you still have not got a result, and remember to be polite and courteous at all times even if you do not like what you are hearing.
Nissan customer services may be able to help as a last ditch attempt, however no point in phoning them unless the parts are covered by the warranty and your garage are being dicks.
Good luck.
Alex.