Hr Wants To Cut My Pay After I Already Signed An Offer And Started Working….and Called Me From Her Personal Phone.

Location: Florida

I need some advice because this situation has gotten REALLY weird.

I’ve been with the same hospital system almost 2 years. I was recently offered a position in a higher role.

On July a recruiter offered me a specific hourly rate, about $2 more than I was making. I received the offer in writing, signed it, and started the new position in early August.
Then I got my first paycheck…and my pay hadn’t changed.
I contacted HR. They confirmed the rate on my signed offer, told me it was apparently a system issue, and said they would fix it and back-pay me. Okay, problem solved, right? NOPE.

About a week or two later, another HR person called me from her personal cell phone. Not her work number. Not an email. HER PERSONAL PHONE. She told me the recruiter had apparently made a mistake calculating my pay and that the rate was too high because of “equity” and fairness to other employees. Now they want to lower my pay.
And not just back to what I was making before. The new rate would actually be LOWER than my previous pay.
So basically, I accepted a higher-level position, signed an offer, started training, worked there for over a month…and now they want me to take a pay cut.

The details that are really bothering me:
1. Signed written offer with the agreed rate
2. Two recruiters confirmed the rate/calculation
3. The calculation was based on my previous hospital experience
4. HR initially confirmed the rate AND said I would be back-paid
5. It’s now been over a month and I’m still training in the new position
6. I never agreed to a lower rate

And then there’s the PERSONAL phone call.

I told HR I wasn’t going to sign another offer because I had already signed the original one. She responded, “So are you telling me you’re resigning?” Ummm…what? ????
I never said I was resigning. I said I wasn’t signing a NEW offer with lower pay.

The fact that she contacted me about my compensation from her personal cell phone was already uncomfortable and unusual to me. Like…why are we discussing my employment/pay from a personal number instead of an official company phone or email? It honestly made the whole situation feel even stranger.
I’m in Florida, and I have the signed offer + documentation. I have not signed anything agreeing to the lower pay.
What would you do? Should I go above this HR person, contact the original recruiter, demand everything in writing, or talk to an employment attorney?
I’d especially love to hear from anyone in HR/payroll or anyone familiar with employment law.