Early unauthorized deduction

I am absolutely seething, when I took out the insurance last year, I stipulated that the premiums should be debited on the 25th of each month. Now all of a sudden, with no authorization from me, I get debited on the 22nd. How??? And then they say maybe I missed a premium. I have never missed payment a day in my life, how do you just decide on your own to do an early deduction?? How is that even allowed? No man this is absolutely ridiculous, it's actually enough to make me want to cancel my policy altogether. I always pay on time and now when it suits you, you just decide to deduct 3 days earlier? Unacceptable! And when I reverse this it's going to look badly on my account even though you are the ones who are clearly making a mistake.