Indoor Pest Control - Bats!!!! Help!!!!

Hey, so I'm a poor college student living in an attic. I cleaned it out and its now the nicest room in the house. unfortunately I have some unwelcomed visitors on occasion. I have killed two bats using a tennis racket after getting the crap scared out of me watching it crawl out of the wall above my bed and I thought that had done the trick but here I am. 4 in the morning when I have to be up at 10 trying to find a solution. I have 2 of the ultra sound rodent repellers and they dont seem to work. I was just wondering if anyone had any tips to help me out. please emphasize the POOR COLLEGE STUDENT part meaning I dont have cash to really put into this. My land lord is no help and was suppose to take care of it and hasnt. I've already got mild insomnia so I really cant be stuck here unable to sleep because I can hear one crawling around on the other side of my ceiling. I know the best solution is to plug where they get in and the landlord did plug up two of the holes but he left the main one because he couldnt get to it and heaven forbid he hire someone. So im basically SOL. Thanks for ANY help

Is there air space that you can get to above the wall/ceiling covering? If so, you may can put some mothballs in the area outside your living space and it will drive them out the hole left by your landlord. You may have to deal with the smell of naptha for a short time, but you won't have bats, or squirrels.