I was in Security, not quite retail, but the game is the same.
I told the bosses I was, for the next few months, not available on the weekends as I needed that time for nonwork stuff.
Then all of a sudden I dropped from my usual 60-65 hours per week to 5... for no other reason provided than they supposedly didn't have any work for me, which I knew to be crap. I had already been working for that company over 2 years and so I gave them the benefit of the doubt, and stuck with it for the next three
weeks. It helped that I had friends whom were able to help out. 5 hrs/week is just not enough to survive on.
Ultimately though I ended up moving to another company, who saw to it that I was working 60-65 hours a week without working weekends, and had no trouble providing what I needed and wanted. I also returned to working weekends when I no longer needed them.
All I can suggest to other Wronged Workers is to try talking with upper management, and if things can't be resolved, then find another place of employment. It isn't worth the subpar treatment and disrespect. You are worth more than that, even if the only one who may see it is yourself. Don't compromise on what you want, no company is worth that.