Arrogance and bad service by FNB!!!

FNB has suddenly started to charge me bank costs in July/August this year. I have opened a Pocket Savings Investment Account of R10000.00 some 2 years ago to prevent bank costs from being charged. When I approached them yesterday egarding the problem, I was told by Christopher who assisted me that bank costs are now chargeable. Not knowing why, he phoned somewhere only to be told that the goalpost has been moved by FNB and that it is now R15000.00 needed in the Pocket savings account to prevent costs. They claimed they have communicated this by giving a months notice to their customers, but failed to be able to show me the letter. I am furious. I have been a customer for 42 years since the days of Barcleys bank and have always been treated nicely and proffessionally. This is a disgrace for my bank I used to love and brag about so much. Are they getting complacent and arrogant like the others? What a shame FNB. I am not of the age where I want to switch my acounts and investments, which makes it even more deplorable. How can you just change the terms of our agreement when I was n ot allowed to do so? Are you getting like Vodacom and Cell C by just changing contracts one sidedly?