It's Me Again Margaret!

Well I have an issue I'd like some opinion on if anyone actually reads this thing... My job is great and I'm very happy with what I'm doing, however, the original agreement when I was hired was that I wouldn't work Sundays unless there was no other option... Now I have worked every Sunday since I started... Until now I've only worked the hours after Sunday morning services but they are starting to schedule me earlier... How should I approach the situation? I HAVE to confront the issue becuase of my call to be a Worship Pastor. It's beginning to interfere with my calling and I don't think that is right at all. So any thoughts would be fantastic. :-) God Bless!! Thanks for your help!