The exterminators got as many bats out from the outside (with a bent coat hanger), as they could. Then, where the bats were getting in, they sealed with foam, . The remaining bats had to exit through the interior of our house!
Those exterminators could have made your life a lot easier. If they identified the entrance that the bats were using they could have easily put a one-way door over it to allow the bats to exit the house but not reenter. There's a pretty good write up on it on page 8 (and the rest of the handbook is pretty good for other bat info) at http://pubs.cas.psu.edu/FreePubs/pdfs/uh081.pdf.
