SHOCKING service from FNB! I've been totally ignored for weeks on the closing of my account

I have been a customer of FNB and given them lots of good business, but all of a sudden my accounts (even my dormant business account!) are being terminated, and nobody from FNB will tell me why or even bother answering the phone or replying to emails. Without any explanation or notice, FNB has terminated my account. I have reached out via emails, phone calls, and to my private banker multiple times, but no one has bothered to respond. This lack of communication is totally unprofessional and unacceptable. All I want is an explanation on why my account is being closed, and if there is any possible remedy that I can implement to stop my account being closed, but nobody from FNB is giving me any answers. I have historically had good feedback from FNB whenever there has been a problem, but with this matter it has been absolutely shocking. All I want is to talk to someone and find out what is going on. Instead, I am left stranded and ignored, with no reason given for this abrupt termination of service. How can FNB expect to maintain trust when this is how they treat their clients?