Standard bank block my account for what i don't know about

Standard bank block my account, i made a contact with them, asking why, they told me that i receive R500 on the 1st of march, i check my statement and i found the R500, they said it was a proceed of *****ulent money that was sent to me, i check my chat history and all conversation, i could not identify the sender of that R500, i went to police station to do affidavit about it and send to standard bank since on Saturday, I even told standard bank to take out the R500 from my account that i'm not interested in funds that i don't know the sender. till now, i did not get a respond from standard bank and my account is is blocked, i'm currently running at lost as i need my account to continue with my day to day business activities, and my trade, all is paused now and i have lost more than R10,000 already because of this,