Debit order going off on incorrect date

Good day, for the past couple of months, my debit order has been put through to go off two to 3 days before my actual pay date. I have signed for my debit order to be deducted on the 25th, if the 25th falls over a weekend, it must go through on the Monday. But for some reason Old mutual is doing the debit order payments before then when there is no money in my account due to the fact that I only get paid on the 25th weather or not it falls over the weekend. As for this month of October, the 25th falls on a Sunday for which I only get paid on Sunday, now due to the fact that this is happening, my bank account goes into a negative balance, then the bank ends up phoning me to make payments and to remind me that there are charges etc as well as me getting a bad credit.<br> This should not be happening, They should stick to the payment date after I have actually gotten paid. If this is not changed, I will bill them for all the bank charges I have been charged on every month they have put my payment through before the 25th.