FNB BUSINESS CLOSED MY ACCOUNT WITHOUT TELLING ME

I am so disappointed with FNB.i have a personal account with them even bought my car with them and have a business account with them .And recently I loged into my profile only to find that my business account has disappeared when i called to ask them why I was told my account was closed yet I never received any communication from them .And now I have invoices that ate due from clients but how will they pay with a close account. I am fed up with service providers taking advantage of clients .I have banked with them from 2013 and this is how they thank me.I am really really cross with FNB BUSINESS.