I definitely agree with you, you need to bring the district manager in on this ASAP. I also think you need to bring HR in on this as well. I know you were skeptical in the post below that HR can do anything for you. However, I have had the chance to work closely with an HR department. Their main concern was always to make sure that the laws/rules were followed to a T. They want to make sure that everyone's happy, if no other reason than to avoid lawsuits.

You have a right to know why you aren't receiving hours. I really hope you do receive an answer.