Start by unsubscribing from the merchant or service itself and take a screenshot or email confirming the cancellation.
Steps
Then, monitor your card; if the charges continue despite the cancellation, contact your bank and provide proof of cancellation and transaction details, and ask about dispute resolution for recurring payments.
Blocking your card alone isn't always the best solution because some recurring payments may be updated across networks; therefore, explain to your bank that the issue is a merchant recurring payment and request the appropriate action.