Unnecessary charges because of lack of customer service

Last week I called FNB life requesting to change my debit order date for my life cover to be on the 20th and also asked that they should remove me from the list of people who will be debited on the 15th as I won’t have money on that date. My debit date is the 20th and I don’t want it changed, also called the funeral and told them the same thing but to my surprise Life cover debited on the 15th leaving me with a charge of R115 of a missed debit order. You can not charge me for your own negligence and lack of customer service. Because I called many days before the 15th requesting I should not be debited. I want that R115 refunded because it’s not my fault that I missed it