Money Missing

I have been banking with Nedbank for decades. I have a cheque account with them and this morning I had R2200.00 deposited into my account, which took my available balance to R2271.23.I then used the Checkers app and placed an order this morning at 09:54AM for R1172.08 and my remaining available balance was R899.15, as per the SMS I received.

I now went online too perform a transaction and my available balance is -R900. I called an spoke to a consultant who cannot tell me where my money is. I am livid right now, I want my money. I think I also need to change banks.