my account and money on hold

Fnb is killing our small business by not protecting us their clients. I am into project and part sourcing services, i recently had an order to source parts worth R126,950.00 to a client of mine(my buyer). Which i took goods of R105,560.00 from my supplier and supp**** to my buyer after i received alert of his payment into my account on my phone, when am about to transfer to my supplier his part of the money i realized that my account is on hold. i have went to my branch and to query why my account is on hold. No body there is even concerned with my issue. The only answer i get is that was R4k that was deposited into my account that was **********. I can believe this stupid reason this guys gave me. This is business account for Gods sake, clients collect my account to make payments, if there is a problem my bank should contact me and to hear my side of the matter. Now people i owe are now threatening my life, i seat with debt of over R105k. I have the invoice of the business with me #FNBmustfall. Mr. Petter pls save us