bank refuse to reserve back money that was wrongly transferred to someone

I was sent to send money to someone's bank account and once I have done that I should call the numbers I was given to let the person whom has deposited the money into the account. Then I only thought since I bank with captitec bank then I should rather do a cell phone banking transfer instead of going to the branch. I did transfer the money and only to find out the account doesn't correspond with the one I was given but the cell phone was correct. Then I called the help line but they failed to assist me up until my airtime finished. Then later on I was informed by the person that sent me to deposit the money that the person has passed away. In the morning I went to the bank to report and the consultant called the head office then explained what happened. Then they said to me they will contact me after 3 working days. Then on Monday a lady called me then told me that they have investigated then the outcome was that they can't refund me cause they can't get authority from the account holder to say they should refund. Then I explained but still the lady went on to say they can't do anything and that I have lost my money. Then I told her that since I bank with them it means my money is not safe cause something like this can happen anytime. Then she interrupted me while I was speaking she was busy reading and then says she will reactor cell phone banking rules and didn't give me a chance then hang up the phone. I called again then I was transferred to her then she said she can't help me any further she has closed my cause and that I knew this person has passed away. So I really need my money back. Please help