Why Didn't My User Get Notified That I Declined Their Transaction?

Though Payment Approval Messages are automatically sent to your Learners when you Approve their LMS Transactions, no automatic approvals are sent for declined purchases.  

If you choose to decline a purchase, you must inform the Learner by manually sending them a Message. If you don't send them a message, they will not be informed and so it is critical that you notify them of this manually.