Conflicting issues

I got two calls from 2 different females saying they are from standard bank and in both times I was unable to get their names because I was driving and the calls got cut. They were claiming that my cheque account was overdrawn by almost two hundred rands. After the first call got cut logged into my app and found out that it was not the case. When the second lady called I then told her to double check my account and she said she was looking at it and it overdrawn. I'm now confused because the app is showing something different to what I'm being told. I'm now even doubting if they are from standard bank but they are in possession of my banking information