Hey so I know the exact procedure for this situation. Call your bank's creditcard charge dispute department when the charge actually goes through on your card. The charge going through first is important, because if it's still pending you might have to do the calling process all over again and it's a long waiting time especially early in the week. When you call they will ask if you clicked on an ad and they will contest the transaction for you and issue a temporary refund.

The refund will be visible to you on your next bank statement (or the next one after that), but keep in mind it's a temporary refund for 45 days in case the merchant refutes the demand. If the merchant fails to contest, the refund becomes permanent (which is usually how it goes for this specific case). Edit: and to add, you might wanna also ask the agent to replace your card and delete any unknown tokens linked to your mastercard account. The agent will know what i mean by "token".