Sounds shitty, how long have you been at this job? Some places promote primarily based on experience/loyalty and there just aint shit you can do to help that. No guarantees hours is nonsense though, thats super shitty.
Over a year as a full employee, however I had been a holiday employee the year prior to getting hired as well.
People have been promoted into this position within months of starting, and it's not uncommon at all in the company to just hire people into it outright.
I'm a fucking "part time" employee who they generally keep one shift short of hitting 40 hrs, but since I have no guaranteed minimum, I could have 35 one week and 14 the next. They know it's my only job, they know I deliberately keep it as such so my availability remains open to HELP THEM, and I am the only part time employee with open availability. It's fucking horseshit.