Just had my nice 11A window seat in Y on DL1533 ATL-RDU Feb 17 blown away.

Also just had DL SMS and Cust Svc supervisor in SLC tell me it was my fault.

I'd selected 11A/11A both legs. My DEN-ATL redeye just got upgraded today. I changed the F seat I'd been auto-assigned to a different one. I did NOT change the ATL-RDU Y seat that didn't get upgraded.

Was online checking a few minutes ago, found it said "No seat assigned" for that flight. Called SMS, they told me "You erased your seat assignment when you changed your other seat". Agent totally clueless about my response "No, I did not erase my seat assignment - your website might have done it due to a bug, but I did not do it." Supervisor likewise couldn't do a thing.

Now I'm stuck in a middle. Short flight, not that big a deal. Though not what I want coming off a too-short-to-sleep redeye.

But horrible website usability. No reason why a seat that was assigned can be inadvertently erased entirely without some warning. It should be hard for a customer with an assigned seat to accidentally de-assign without a new assignment. And the site shouldn't accidentally do it. There definitely should be a "You are deleting your seat assignment and may be unable to preassign another seat - are you sure?" messagebox at minimum. Actually, I don't think you should be able to go from assigned to unassigned state at all via the consumer website, but if DL feels this is a necessary function, it certainly shouldn't happen without a warning.

Especially when the agents then blame the customer. That's a CS issue which I'll take up with the appropriate channels, but the accidental assigned-to-unassigned state change is a website bug. Wouldn't have happened on NW's superior website.