Careful! FNB they just sell your shares without asking!

I just received a noticed from FNB saying that they have sold some of my shares - this being without me doing so or anyone hacking into my account, etc. So the obvious next step is to give FNB a call to find out what is happening with the account. The friendly guy on the other end of the line (without confirming any of my details) goes on to tell me how FNB makes a decision on your account to sell shares to recoup account fees, a measly R100. Not once have I received a call, email, SMS from them to notify that this account was sitting in a negative balance (even though a small one). I am appalled that a bank thinks they can make decisions like this for us - WHO THE HELL DO YOU THINK YOU ARE FNB!!! An outraged and appalled SA citizen