Took my December Bonus for monthly instalment

So I phoned on the 14 Dec the call center for African bank because they where trying to deduct my monthly installment . Which is also schedule to go off on the 25 of each month. I told the lady helping me that it is trying to go off and it's costing me exstra money because it's coming up on my bank as unpaid. I also explained to her that my Bonus is going in on the 15th and that it is going to take my Bonus money for the monthly installment. She even asked me on what day can it go off then we arranged for the 24th Dec. 15th Dec African bank installment went of and took my full Bonus. I phone them again and explain to them that I did arrange this yesterday. Although I didn't even receive a message or anything to say that they are going to deduct my installment. They then put me through to another department. The guy helping me said I have to sent them 3 months bank statements to refund me my Bonus. I am at work and don't even have transport. I told him it is not fair because they took my Bonus and now I have to make the plans to get it back they should correct it because I am aware that installment should go off on the 25th. African bank didn't help me at all.