FWIW, Sig's rep is kind of in the dump right now. I've had nothing but good responses from them whenever I have called them for CS needs. Others, however, tell much different stories. One of our LGS/range used to be a hardcore Sig depot and all but dumped their Sig business based on souring satisfaction with their corporate/distribution relationship.
I did have a gunsmithing issue in which I returned an upper for an unacceptable condition and it was returned right back, very quickly (as in, I don't know if they even took the time to look at it), and in the same condition as it was when it left my hands. I immediately e-mailed the CS person that I had been in contact with since the beginning expressing my dissatisfaction of being told that it was "within spec" and he immediately apologized, sent out a new shipping label, gave me his best e-mail/written guarantee that it would be inspected and fixed by a master rifle smith, and two weeks later it was in my hands, problem solved.