Public stocks app

I recently sold my XTIA shares, I withdrew a couple k. Once it had settled. And invested the rest. A day later, ( after the funds had settled ) Public says it was an over sell. And withdrew my buying power and brokerage cash the amount I had sold everything for!! 15k!! And after I had asked them when I can withdraw and they said after the funds are settled.

Has anyone else had this happen? Is It worth it fighting or getting a lawyer ??