Unhappy customer

I am writing this because I have had no satisfaction dealing with the call center . I recently got standard bank mobile sim and for the past two months have been getting debited on the wrong date which is the 20th of every month. I have explained to the agent that i do not work for the bank so i cant be debited on the 20th because it puts my account in arrears and makes it difficult to transfer money "that time of the month". I have also informed the agent that i get paid on the 25th of every month. When getting the sim card standard bank did not contact me to ask when the should be debiting. i asked the agent to reverse the transaction she said no i have to make a payment into my account.