Enough is enough

I have been banking with FNB for almost 10 years however I am disappointed in their service. They do not want to reverse unauthorized debit orders that went through on my account on the 15th of November because they have had a system upgrade which is causing the said delay. I have had to live on short term loans due to this and my account is currently sitting on a negative balance because of dishoured payments due to their delay. What is unfair is that they expect me to pay for all the charges related to these dishoured payments. Have been calling them since the 16th of November 2019 without fail however everytime I get different explanations from their staff.