Disappointed with capitec choosing their own date to take off the monthly installment when I do not get paid on the 27th every month

Extremely disappointed with capitec. I have been banking with them for the passed few years. I recently took out a personal loan and captiec chooses to just take their own date to take off the monthly installment. I do not get paid on the 27th of every month, the salary date varies. I called to change the date to the 29th of every month and I was told it is not possible. It is negatively impacting my credit as it shows I am in arrears. I will not recommend capitec to potential clients and I am thinking of changing my bank.