Bank account frozen

Hello Peter Soi joined this online business which I invested R400 and I was paid R843. 90 in return, after that fnb send me an email stating that my account was reported to have received ********** funds and it was put on hold. I don't understand how, it is ********** because I invested my money and got my yields. I emailed the agent who is handling my case and he never responded, I emailed all, the proof but still no response. It's been a month now