The secure payments page provides absolutely worthless messages to the end user:

"There was a problem processing your transaction. Please contact us before submitting it again."

This message for example doesn't help at all when the donor is using a non-supported credit card type.  She gets the message, and contacts us.  I look in BBMS and the transaction attempt isn't there at all, so I can't tell her what went wrong.  Finally figured out that she was using a Discover card, which we don't accept.

We would like the OPTION to be able to give more detailed error messages to people.  Especially in cases like this.  At the very least, we should be able to tell them that the credit card number was invalid, or the gateway declined, so they know it's not our fault.  We don't want them contacting US in such cases.