Standard Bank - withholding cash that belongs to me

My elderly father has had an account with Standard Bank for more than 45 years. I have power of attorney on his accounts. He is currently overseas and I transferred money to him from my account with another bank. Without any notification his account has been closed, as they say they can't keep it open unless he had a regular income coming into it. That was on 15 March, as of 4 April I have been unable to pay the get my money back from Standard Bank. They will not take responsibility for this and tell me to deal with my bank, however, Standard bank still have the money, and have not transferred it back to my bank. I have provided all necessary information and am not having any success. How do I get my money back?? Is this the way to treat long standing clients who have been loyal for 45 years? What kind of client service do you call this?