Kindly do the below steps ASAP.
1.
Block the merchant on which you noticed fraudulent transaction
https://karboncard.freshdesk.com/support/solutions/articles/81000390848
2.
Lock your card
https://karboncard.freshdesk.com/support/solutions/articles/81000391067
3.
Send an email about this transaction to support@karboncard.com
We can then issue you a new card and investigate this issue.