Missing money

On Sunday morning I discovered that my account was in the negative of around R1 600.00. This was impossible and when I refreshed the page the available amount in my account kept changing. Since Sunday I have been unable to buy electricity or food as it shows that my account is in the negative, which it is not. I went to the FNB branch this morning looking for help. They do not assist you in any sense and merely point you to the telephone to call general support, which I did. I was informed that it would be fixed during the course of the morning. It has still not been fixed. Due to FNB's "technical problems" I was unable to buy food or electricity for more than 24 hours and am therefore still in the dark and have no food. This is not okay.