Clarify declined donation messaging

Donations with a verification error (such as an error in card number) don't receive a declined response like in RENXT forms. If the card is declined, the donor receives an email that the gift is still being processed. The email stresses that the donor will be contacted within 24 hours - but if it is officially declined, the donor receives NO communication.

Please add a declined email - or at least prompt us at the charity with the donor's contact info so we can reach out to the donor or fundraiser. The donors think they've already done what they need to do and need to be notified.