Ok,
gonna make myself even more popular here.
Let's make an analogy with computers. Imagine you bought a computer, 1 year warranty. It breaks down after 2 weeks (shouldn't happen, but hey, that is why there is warranty!). They take your computer and you cannot use it for 2 weeks because they need to look into what is going on, order parts, fix it etc etc. Then the question is. Is it the end of the world to be without a pc for 2 weeks? For a lot of people, no. For some people it could mean bankruptcy because they need it for work. Then the question is, if the "asset" you are using is mission-critical, shouldn't one take extra insurances to make sure that in case of a break-down you are being helped ASAP (like HP's next-day repair service, which costs extra of course, or some extra insurance on the car giving you a replacement as soon as the car breaks down).
I agree it might seem stupid that it takes 2 weeks to get a bloody fan belt (a friend of mines audi broke down and it took them 2 weeks to figure out that due to coil pack failure the car's computer decided to shut down everything to avoid engine damage .... Reset and it was running again), but who's fault is it that it took so long? Maybe at another Nissan garage it would take the same time. Also courtesy cars are not included in warranty (they just warrant to repair what breaks afaik). My guess is that if you had gotten one they would charge you for the time you had it. Try figuring out first if it were the "muppets" in the garage that caused the delay.
THIS on the other hand is stuff which you can/shouldcomplain about. I hate it when ppl promise to call and they don't (especially when it is a girl )