Charged on closed Discovery credit card account

Good day,<br> I cancelled my Discovery Credit card on the 19 Jan at FNB after the account was settled in full and was advised that the card has been closed. On the 18 Feb I received an SMS notifying of exceeding over limit of R1325.80 with FLYSAA I informed them that their card is not in my position since it was requested and destroyed at the branch. I then requested the agent to confirm the status of the account and was advised by the agent that it is closed however an authorisation was processed on the account. The agent transferred my call to ***** and investigating department where I was told that they will investigate the matter. On Thursday 19 Feb and on 21 Feb I received a calls demanding of payment, I then informed the agents that the account is closed and the Discovery investigating team is busy with the case. On the 26 Feb I then received another SMS notifying me of exceeding R2652.6 amount on the credit card. I am not going to pay or settle any account that I did not use, not to mention a closed account<br> Please credit and closed the account.