Discover Reason Code NF

The cardholder says they never got confirmation that a recurring charge was cancelled.

A subscription cancellation was requested, but confirmation of the cancellation wasn't sent or received.

An outdated code name (fax), but the underlying issue — proof of cancellation confirmation — is common with any subscription.

Record of the cancellation confirmation sent to the customer (email, account log).

Not sending an automatic, logged confirmation when a subscription is cancelled.