I am a liitle bit surprised, did delta changed their comfort+ lately? Last time we have flown delta (2016), we could upgrade our seats to comfort+ for maybe 100 euros for our flight from Paris to New York. Yesterday we have booked a flight from Paris to Atlanta for February and we couldn‘t choose comfort+ seats. We have a Main Cabin Ticket (booking fare x) so an upgrade should be eliable, but when I tried to choose C+ seats I got an error Message, that I have choosen Main Cabin and therefore I am not eliable for C+ seats. Even now, a day later, I have no Option to choose C+ seats or buy an upgrade to comfort+!
I asked their twitter helpdesk and they told me, that I can book an upgrade via phone, but not for a seat, but for the DC+ class...but the upgrade would be 3 times as much as I paid for the original tickets! Is this correct? Is C+ now 10 times more expensive then 2 years ago???