It's very easy to do yourself, and it 100% works! I have used this to get rid of Carpenter bees my whole life. You will need a can of WD40 spray, the one with the long sprayer tip at the end works best.
Spray the WD40 into each bee hole. Spray a pretty good amount, and the bees will fall out and die. This will keep the bees gone all year long.
