Have the St. Regis handle it for you. That way, you know that it will get done and that all you need to do is leave it out to be picked up and the next thing you will see is the garment when it's delivered.

Any large hotel throws a lot of tailoring business and their tailor -- they may even do it in house -- has every incentive to keep the property happy. OP, on the other hand, is a one-off.