Need to vent...

Okay, so for a long time, my boss had been suggesting that I become a Care Team Leader...basically means that your one of the unit's resources...you're in charge a lot, etc. Well...since I'm one of the more senior people there, I'm in that role most of the time anyway, just don't have the label. I also work part time (60%). I said I wasn't willing to go full time if I didn't need to because I didn't want my kids in daycare any more than necessary. So anyway...I had to wait until they "posted" a care team leader position, and apply for it like it was a new job (I wouldn't be changing units or anything). So, a position was posted, only it was for 80% and straight evenings. Again...my manager said to "just apply for it." I told her that I couldn't do 80% and I wouldn't do straight evenings. I dislike 8 hour shifts...they would require me to work additional days. Anyway....I was promised that it wouldn't be a problem, and that "we'd work it out." I agreed to go to 70% if they changed the straight evening part. Right now I'm technically day/evening rotation...and I do 12 hr shifts, 7am to 7pm. Moving on...everything was agreed upon by my manager that I would do 70% and stay day/evening (even though the position said eveings...she was going to change it). So, I accepted the position and was supposed to change roles August 3. Today I get a phone call from my manager saying that they weren't going to "let" her change the position from evenings. Now, considering this was a term of my acceptance...I was a little miffed. I actually couldn't say anything at first, because I had started to think I was stuck in the evening spot. Anyway...she said she would offer me my "old position" back if I didn't want to do the evening thing. I was like "of course, I'm not doing straight evenings if I don't have to." So, just like that they renigged on the promotion. I'm starting to think I need change....just not sure what kind of change. We get a new manager in a little over a month....will that be enough change? I dunno.