You should start with a visit from an exterminator. He may be able to help slow down the Carpenter Bees. It will take a monthly visit from him to really help control them, but you will never really stop them. Once you get them under control the woodpeckers should stop visiting since their food source will be gone.
If you need the stain re-done or stripped and re-finished call Mike at 866-670-3020 for help.