it happened to me a few years ago, I won on a little bit similar situation to Memphis (different book) and cashed the whole account out (making a run for it LOL), I logged back in a few days later and had a negative balance which I didn't think was possible LOL, we then had several discussions back and forth and we eventually compromised with some money returning back and a rollover requirement added which I ended up fulfilling so it was still profitable in the end, just be polite and work with them and stay calm if they try anything