10 Days early on debit

Please could somebody at African Bank explain to me how with no correspondence of early deductions in December, do you have the right to deduct a debit order due on the 25th, on the 15th!? This is'nt the first time though, we have clearly stipulated to them before that the debit is to be taken on the 25th of each month and if the 25th falls on a weekend or holiday, then they are to deduct on the 1st working day there after. We keep to our side of the agreement and have never defaulted in any payments and we would like to know what recourse we have against African Bank for not honoring their side of the agreement? They have now taken all available funds out of our account, leaving us with no money until we are paid December salaries which is paid at the normal time for us and no earlier. Please explain how we are going to feed our children and get to work with no money for food or petrol.