Old Mutual debit order dates

My debit order date on my funeral policy is set for the 25th of each month. Since 2019 I've noticed that they take my debit order on any date that suits them. This is a huge inconvenience for me because they normally take my last bit of peteol money I leave in my account that's supposed to take me to the 25th when I get paid. I've sent numerous emails since 2019 just to be told "your debit order date is set for the 25th" This month my debit order went off at 23h22 on the 19th of January and as usual they take my petrol money for the week! I am at a point where I want to cancel this policy. Please explain to me why my debit order went off on the 19th? Who do I speak to at Old Mutual that will make sure my debit order goes off on the date as specified by me? Please advise?