unauthorized debit order keeps debiting account even though i have queried with the bank

I have been having a problem with an unauthorised debit order for months now, last month i wrote a review here and FNB promised to phone me to sort this out for me , to my surprise the very same debit order i have queried last month and cancelled has debited my account, what type of service is this one where our money is not safe? i am thinking of closing my FNB account and cancel all the account and policies which i had for more than 20 years with them, i cant go on like this , FNB failed me not once but many times .