Advise

So basically I currently have a part time job that I was informed that I'd be getting 15-20 hours a week. I've been getting basically 0 hours (store hours cut everywhere) and I don't want to walk into the same thing. I just don't know how like professionally ask if the hours that they tell me I'd be getting is actually consistent and not being told later that oh those hours we quoted you were average and then oh we don't have hours you'll have to call other locations.