Unexplained transactions

My recent experience with nedbank is becoming a nightmare , past two months I have been getting a minus on my account and I don't have an over draft worse part the won't be any transactions going through to account for that minus. I called in on the 9th/2/23 and two tellers couldn't even explain on what's going on and none of them offered to investigate. Even called the ***** services still they couldn't explain. Later went to their complain line to raise the issue . Celeste later called me .she couldn't even come up with a proper explanation for all that and she wouldn't listen to my points . She talks as if I don't know how my account works . I've been with nedbank for as long I can remember and I don't remember experiencing such and I know that if my account doesn't have money it declines .I'm so unhappy with the service . I don't think their transparent about all this . I hate a bank which is not transparent . I need them to do further investigations and tell me why the sudden change in my account and stop talking to me as if I don't have a clue when it comes to how their banking works .I also feel like if I leave it like that , they will be doing this every chance they get.