Bad experience

I paid money into a wrong account, and when i went to ask for a reversal they told me that they are able to see that the account is active but wont help me because I am not their client. I asked them to at least let their client contact me because i cannot legally get their contacts from the bank, but they told me there is nothing they can do. Of all the mishaps i ever had with a bank, it has always been FNB, and that began while I was still their client. That is why I will never open an account with them ever.