We hired an exterminator. Nice thing about Carpenter Ants, it is a "once and done" effort. I remember being able to hear them chewing in the wall of the family room.
The primary nest is likely located outside, near a wood pile or in the ground. They travel far for their supply, and may have a secondary next near / in your wall, but the primary one is important to get rid of too. That is one reason the home improvement kits don't work that well.