Account frozen

I have been with FNB since 2014 and had its good and bad treatments but this is by far the most frustrating. A client paid me R10 000 on the 28th of August for services and my account was frozen 2 days later with no explaination, After calls i was told someone was assigned to my case and had requested reason for the payment and i did send in my invoice and pop as per request and im yet to recieve any feedback from fnb and when i call im told the one handling my case will call me back and hasnt still. And its infuriating that were been puniushed for what others do with theyre banks and all we do we provide service and if they suspect foul play on clients they punish us selectively and never freeze all the accounts people they suspect got the funds in a suspicious way, they never freeze school accounts or even multi choice or car payments but freeze mine even if i provided all supporting documents and now im businbess isnt able to receive or transact and conduct business for a whole month.