IBTP informed me today that there’s a $1,700 "equity settlement fee"

This is Stock Index Futures Positionsnow the fifth time they’ve asked for an unexpected charge.They argue it’s necessary to “equalize portfolio valuations” before liquidity can be issued. What does that even mean? I’m not part of any fund—I just want to withdraw the money I deposited and earned.I feel like they’re just stalling, hoping I’ll keep paying. I’ve asked for legal documentation showing this is standard practice, but of course, they didn’t provide any. Just more vague promises and reassurances.If anyone has successfully dealt with this type of situation, please reach out. I’m desperate to resolve this and get my money back.