Debiting My Account on Unauthorised days and its costing me

I have a bad experience with Capitec debiting my account on days before the actual debit date, I am incurring more than R300 bank charge fees for their inconsiderate action, I know I'm behind with my loan repayments but i never get through their call centre number to make arrangement and incurring so much debit charges is making it difficult for me to work away my arrears. since January on a monthly basis they debit my account before my pay day and the debit order returns because theres no funds i have to carry those cost, with financial situation this is the last thing I need, moreover they are making difficult for me to recover from this financial stress