Rightly so. A good CS rep NEVER tells a customer something like that and if she did, she needs some training - some very basic training.
Over the years I have seen some pretty poor attitudes at S&W when I have called in asking for help. It is better now than it used to be, or at least it seems so, but in my opinion they have been far from perfect in the past and the mentality that they can be erratic when they answer CS calls still seems to be alive and well. There is just no excuse for stupid CS responses, even if the inquiry is less than polite. (And I am not saying the OP was; just stating a principle.)
I believe the OP is having some sort of problem with his Shield that we cannot divine from his writing, particularly his opening post, but it also appears S&W did not do their job when he called. If that is the case I do not blame him one bit for being angry. I hope his local shop can help him get things straightened out.