Worst and money hungry insurance

I have had an discovery insure policy for over a year. I got a new vehicle got it insured as I did not have a problem with Discovery before. I changed my debit order date from 15th to 25th. Discovery to the pro-rate on the 1st of October. They tried to debit my account from the 15th(even though I changed debit order date) they tried multiple times. Then on the 25th they debited over R1400. I havent even received my feul reward for previous month. I have called the call center. They asked for my bank statements, I send them the proof and got an email stating everything is sorted. how can it be sorted if they keep deducting money from account when I specifically showed the proof that I havent received any rewards and they double debit my account for a pro rate.