Held to Ransom by Shocking Service!

I've tried to reach FNB Business Banking for over 3 weeks now to close an account and nobody has bothered to contact me. I left a complaint on the FNB site 2 weeks ago, got a call from an agent and since then again... heard nothing. I've asked my personal banker for assistance, was ignored the first around as she "thought the email was addressed to someone else"... and again, I've heard nothing back. So I'm stuck with an account don't want and I cannot get hold of anyone to close... I'm being held to ransom by shocking service.