2006 Mazda 3 engine noise

I went to the mazda dealership today, and like what i've always heard them say: "we can not hear the noise; therefore, we can not do anything."

the noise is driving me insane, it's like a chirping noise when the engine is low RPM while driving (roughly around 1500). Should I just find an auto repair shop and change the stupid serpentine belt? Or could it be something else as well?

P.S.
The noise is most noticeable when driving around 60km/h at 1500 RPM

Thanx.

Keep taking it to the dealership if as long as it is under warranty, make sure they give you a written statement of your complaint and what they do or do not find. If they hear it one of these times and fix it then great, if not you have the records of the problem and after a few times of taking it to them if they can not find the problem or can not fix it you can call the manufacturer and they will usually find it and fix it or replace the vehicle under the lemon law.

Or you can (after taking it to the dealer a couple of times) take it to an independant shop and see if they hear the noise, get a report and the take that to the dealer.

Or after the warranty is up you can pay out of pocket for the repair because they will find the problem when it is on your dime

Well, dealership finally caved in, they agreed to replace my engine short block. I'm not sure what that means, what does engine short block do anyways?