Unauthorised debit by Capitec bank

i am customer of Capitec bank for 3 years plus now and the service that i received is shocking and appalling .i have a personal loan with the bank which is supposed to debit on the 15th of every month.i had a money deposited in my account on the 11th of February 2019 from a relative for some personal business to conclude.on the same day within 30 minutes my account was debited of my monthly instalment.mind you the 15th is this Friday, I remember very well when i signed the contract that they will debit my account on the 15th .this is a very unusual and unacceptable trend,my wife has been struggling with the same,though they have reversed the amount when i called i am still not happy with this kind of service.

i am really considering banks if this issue is a common train on capitec.