I'm surprised that you have not received them if they stated they would send them out. I have many sigs and have dealt with Sig CS on a number of occasions over the years and must say I have never been wronged not once.
The fact that SIG has undergone some changes is true and hell anything is possible but I'd be surprised if you give them the S/N of a new gun and asked for nicer screws etc. that they would honestly not send them.
I had a slide replaced free of charge due to a cosmetic issue without ever doing more than sending a few pics and shipping the whole gun to them, Did I mention IT WAS USED when I bought it!
Yes they knew this fact...Victoria is that Lady I have dealt with a number of times over the last 5-10 yrs. maybe, she was always very helpful
I hope you get what your after but even if you don't you will have a easier time coping when you give it that Ding or scratch
Maybe just buy another ...Shoot one, Fondle other