Can you please help

Hi I'm the owner of bricks manufacturing business(Desvilla Bricks &Sand)and i use capitec bank merchant for customers who purchase using cards,I'm banking with First National Bank for my business. On the11th of june 2022 a customer purchased bricks using a card and three days later capitec bank transferred the funds into my account i wanted to pay suppliers but my account was frozen by First National Bank for suspicion of *****,i called Fnb several times but i didn't get help. My business and my livelihood has been affected badly by this situation,can you please help to resolve this matter.