FNB UNFAIRLY DELAYING UNLOCKING MY ACCOUNT

My account was locked by FNB, due to account overdrawn, SARS paid my refund on the account, bank deducted their (overdrawn) amount, but they telling me to wait 24 hours, for me to for the hold to be taken off, Question is if the the account wasn't locked will this 24 hour apply, not at all as I would have be able to access the account,

This is their rules on the money that is due to me? at this moment am actually very angry on this, and want it resolves asap. SARS wouldn't have sent money that was not due to me.