Taking money from your account when they feel like it

Standard bank Life insurance takes it upon themselves to decide when they will debit your account and presume that there wont be funds for the set date. Debit order is loaded for the 26th of each month. Standard bank thinks it is ok to debit account on the 19th. When questioned you are being told that there was a system error with the billing. I mean really 2 months in a row???. I was promised a refund but still waiting. Quick to take but not quick to refund