Did My Job Do Something Illegal?

I work in the state of Texas for a check cashing company. I’ve been working here part time since February 2024. I applied for a part time position, I have a full time 9-5 already so I have never since I started at this company ever worked full time hours nor did I ever state I wanted to be a full time employee.

At the beginning of this month I noticed in my employee system that I had accrued 8 hours for a floating holiday - I worked Christmas Eve and Christmas Day, so I knew this most likely stemmed from this. I was a little confused because I assumed part time employees do not get days like this, so I asked my supervisor and she simply said if the hours are there, they are for you to use. I put in my floating holiday about a week and a half before the actual day I wanted off and my store manager approved it. About 3 days before my day off, I received an email from the company benefits department stating that my status had been changed from full time to part time. I didn’t initially think anything of it and no one told me anything about whether this would effect meim any way. Again, at this point my day had already been requested, reviewed, and approved. Well, my pay check hits last night and it is nowhere near what I was expecting. I reach out to my store manager this morning and he says that payroll did not approve my hours because I am a part time employee and I do not qualify for the floating holiday. Aside from being extremely unprofessional, is there anything I would be able to do from a legal standpoint to fight for this? I’m very upset and was very much counting on that money to cover certain bills. What can I do?