We received a mailing from Southwest a few months ago with codes to reduce price by maybe 10 or 20 %. That was the only time we received the. Used them on a trip to PHX....no DING!s came through so took what I could get.
Related to the DING!...if there is a DING! out there, it takes a while for your computer to poll for it. For example, when I came home today and turned on my computer, it took about 10 minutes to DING!. I tell people to just turn on their computers and go do something for 15 to 20 minutes. That's usually enough time to get DINGED if there is one available. YMMV.