I just struggled through this glitch twice changing two separate reservations (not related to the ongoing $25/50/75/100 sale). The modification page is extremely messed up!

After pulling up the existing reservation and changing the dates and flights, I proceeded to the payment page, and used $30 in tickeless funds from another res, which showed up as being credited, and indicated a $00.00 balance. However, that page would not let me proceed to a final purchase without credit card info entered, even though the balance due is -0_. So, like the OP, I struggled with the OOPS! message for four or five tries (because after applying ticketless fund, the next payment page won't take the CC info), and at about the sixth try, the new reservation showed up with the same confirmation code as the prior reservation (thus preserving my EBCI fees!). Aha!, I thought -- DONE! But no...

The problem now is that they charged my CREDIT CARD for the additional $30 and did not apply the ticketless funds that the res page had indicated had been credited, leaving a -0- balance.

Second try to change my husbands existing reservation: could not get past the OOOPS! message re: credit card info after applying ticketless funds. Just spent 20 minutes online with SWA, who fixed my husband's res, but could do nothing about the $30 erroneously charged to my credit card. Instead, they directed me to call Customer Relations in Dallas, at 214-792-4223.

I told her about this topic, and she said she knew; they were getting lots of screw-ups today regarding this problem.

So, no, it's not fixed...

Oh, and the first thing CS suggested was for me to simply cancel my prior reservations, rebook completely new ones with a new conf code, and apply the ticketless funds. No, I said, that will cause me to lose $40 in EBCI fees -- I need to keep the same confirmation codes! CS informed me that the ECBI funds would be LOST, even on the same conf code, if I changed the flights! No, I said, that's not what your FAQs say... Put on hold for a few minutes until she checked it out, and now I have ECBI on the new itinerary (at the same conf code). Just a heads up -- check your EBCI after modifying a res on this screwed-up webpage!

Someone should warn the CS people about the loss of EBCI credit when they advise folks to cancel and rebook!