I feel your pain. When I did the FCM upgrade from a coach Q fare to D1 for $799 in the middle of the day on Monday, I spend about an hour and a half to get it done.

First the app, then two computers, using both Safari and Chrome, trying to pay with miles when two different credit cards repeatedly didn't work (delta.dumb would only let me enter a three digit security code, not four digits as AmEx requires and kept deleting my expiration date, etc.). I tried to call the (IT?) support number showing on the error page, but the recording said my wait time would be 41 minutes. (I think it was even longer when a person came on the line as I was finishing the transaction.) I then called the DM line on another phone and waited maybe 20 minutes (versus their estimated wait time of 13 minutes) to get an agent, who was wonderful. She was determined to make the upgrade work and could see the $799 offer, but she also had problems making the system accept my DL Reserve card for payment, although she could apparently see it as the primary card on my profile. )I was only seeing several outdated cards and had to keep entering credit card numbers by clicking on something like other forms of payment for each attempt, and then delta.dumb kept asking me for an "alias" which I don't understand; it wasn't a required field but wouldn't let me proceed without filling in the box.) Finally the DM agent got it done (while she was waiting on hold for a support line or supervisor to help her) and I received a receipt for the transaction and a new ticket number by email. I wish I could have sent that agent a big box of Godiva chocolates for her persistence.

My next battle with delta.dumb will be trying to re-update the credit cards in my profile. You would think DL would be happy to have me pay with a DL credit card.

I was on the verge of just cancelling my ticket. Over the weekend, someone removed (not changed) my seat assignment, I suspect late on Friday before the change to the 8777 flight number. Of course DL refused to evict the person to restore the seat to me or to evict someone else from a more-or-less equivalent seat. It wasn't a special needs seat, so I was starting to think how bad I would feel to be in a bad coach seat next to the lavatory for 6+ hours knowing that DL considered someone else more important and willingly gave them the seat that I had carefully picked. However, on Tuesday (yesterday), I temporarily saw my old good seat vacant, so it further seems strange that DL would evict a DM for someone who wasn't very serious about taking the flight at the last minute after all, maybe a blogger/vlogger/social media influencer. It's too bad I won't be able to see who DL decided should be given my seat rather than me.

The incident is making me feel very differently about DL, and not at all in a good way.