Deducting premium before the agreed date

I have a funeral cover with hollard, and the agreed date to pay my premiums is the 25th of every month, now for some stupid reason they decided to deduct the premium on the 22nd for this month, abd because my bank account had insufficient funds, this premium bounced and the bank has charged me R100 extra and my account is on minus. I am trying to build a good credit record and this is not acceptable. Deduct the premiums on the agreed date otherwise what is the point if you can just invade my bank account anytime you feel like.