If you are currently in production with or even considering using any traditional Christmas song in your commercial, stop. You will not be heard. Your target audience, upon hearing the first few bars of your commercial the second time, will reach for their mute button. You might get one listen-through but from that point on, your annoying bastardization of a traditional Christmas favorite will be on the mute button from the second it is recognized.
We don’t like songs that have been beaten to death and then made to serve your purposes. It’s very annoying to hear a familiar song that has been re-purposed to something as useless as a commercial jingle.
And we won’t listen to things that annoy us when we have the option not to do so. Every TV/radio remote I’ve ever seen has a mute button it. We use them to battle the constant stupidity that you fling at us. However, occasionally, and very rarely, you come up with something that can be heard without gagging. You might want to do whatever it is that you do to figure out what those rarities are and make more of them.
But, leave Christmas carols alone!!