I feel your pain. I had a family of squirrels in my attic and of course the hole they created to get in was on the outer most corner of highest part of my roof. Once I was sure they were out and about during the day, I climbed up and filled their hole/entrance with expanding foam. (The kind used to fill gaps around water spigots.) It took two cans and some patience, but I got it closed up. That evening, I had some very confused and unhappy squirrels running around on my roof. After a few days of trying to eat through the foam, they gave up.
