Very livid customer

I had a transaction of 16K authorised/reserved for a vendor on the 26th October 2019. Later the same day I phoned the credit card department and cancelled the authorization. I was assured that the transaction would be reversed which it was as the money reflected on my app the next day. A few weeks later I noticed that an amount of 16K was deducted from my credit card. I phoned the credit card division again and was told that on the 26th of October there were 2 transactions, one which was authorized and then cancelled/reversed and a second transaction without any authorization. My questions is, if the authorized transaction has been cancelled who authorized the second transaction. I also asked to have a copy of the audio recording which I am still waiting for. How are we as customers protected against ***** by ABSA. I am very disgusted with what happened and the way I have been treated. I am seriously considering changing my bank.