A.W.
You can't keep going like that and they've had more than enough time to find a replacement. I would walk in and tell them that you have a job, school and family and last you checked you can't split yourself in half and be in two places at once and that they had more than enough time to replace you yet they haven't bothered to and you are so out of there. Or if you don't have the heart to do it...I wouldn't mind making the call for you...what's the number?