Frozen account with no explanation

Hi standard bank has been no help to me. They froze my account without any explanation. I have went to the branches twice sent emails and made calls with no help. They keep saying they are investigating but I'm not getting any reason. I can't access my account my debit orders are bouncing. I am sick of this. I can't send money home I can't do anything. I did not do anything wrong with my account please I need my account fixed. What is it that I have to do to get help? Iv been a loyal customer for more than 10 years but this is totally unacceptable. I need to use my account. I'm currently abroad I left the country with my issue still not fixed. It's been more than 2 weeks now with no answer from them. What must I do?