debit order confusion

I got a home loan at Standard Bank and signed an agreement that they will deduct on the 27th of each and every month. from October last year they have been doing that and recently things have changed I have to call them and ask for them to deduct. It is the 4th today and they have not deducted I was told their debit order takes about 10 days that did not make sense because in the past deductions went through on the 27th. All I am asking for is for them to deduct on the 27th I dont want to be in arrears.