I recently purchased 3 "silk" turtleneck tops. I normally wear a M, but they were a bit snugger than I prefer. I exchanged them for a L size. No problem with the original order or the exchange. Customer service is very responsive.
So why the 2 star rating?
First fit: I am only 5'3", 130lbs. The body and sleeve length are both too short to wear as a top alone. They will be fine under a sweater. But that was not my purpose in buying them.
Second: These tops are not silk. They are only 35% silk. The remainder is 65% rayon. I did not see that mentioned anywhere. I would not have made the purchase had I known.
Since I did not discover the fabric content until preparing to launder them, and thus had removed all the tags, I will be keeping them.
Live and learn, I will ask more questions in the future.