Appalling service from Bidvest Bank

On Tuesday, May 5, Bidvest Bank double-deducted two amounts of money from my account, leaving me overdrawn and unable to use my card. I discovered the minus amount on my card on Saturday when I needed to get groceries and pet food. I phoned Bidvest Bank immediately and asked why my account was in arrears. I was sent dispute forms, which I filled in and sent back to the bank. On Monday, I phoned Bidvest Bank AGAIN. They said the department that deals with disputes did not work at the weekend. Lucy, at "customer care" confirmed it was a mistake by Bidvest Bank (I thought the retailer might have double-deducted the two amounts) and said she would escalate the matter. On Tuesday (a week later), I phoned Bidvest Bank again. Lucy told me the matter would be resolved by May 20!!!!!!! Seriously??? I asked to speak to the manager - she/he was "on a call" and would phone me back. She/he did not. On Wednesday, I phoned AGAIN. Lucy said the manager was investigating the matter and would call me back. I said that was not acceptable and wanted to speak to him/her immediately. Lucy said she would get someone to phone me back. Of course no one did. It's now Friday and I still have not heard from Bidvest Bank and my card is still in arrears and I can't use it. To say that I am furious is putting it mildly. I am a pensioner (without a pension). I do not have a job. I am in desperate financial straits and my problem with Bidvest Bank is adding to my depression and anxiety. I can't buy food for my animals or for myself! How much longer do I have to wait before Bidvest Bank responds? (I only put one star because there is no option to put NO STAR)