Poor customer service

An unauthorized debit order went through my account on 30/12/2022 & I immediately informed my bank telephonically and physically went to the bank. To date, I haven't anything from the bank. Funny, the amount was more than my balance but the bank honoured the debit order. Automatically my account immediately had a minus balance. Days later instead of me getting an update regarding my case, the bank sent me an sms to fund my account since it's in a minus. Today I tried to do follow-up and I didn't succeed. Can someone from FNB kindly assist.