Yes, if you have the Send Alerts  setting set to Preferred Transactions, you'll be able to block and unblock specific merchants or types of transactions. Please note, blocking a merchant or type of transaction will prevent you from toggling the corresponding alerts.

To stop payment, you need to notify your bank at least three business days before the transaction is scheduled to be made and your bank may charge a fee. The notice to stop the transaction may be made orally or in writing. A bank can require written confirmation of an oral stop payment request.