Originally Posted by
Bowgie
This is true. I'm a diamond and can't select domestic economy plus when I use a voucher to pay for a ticket. The solution is the same as johnslloyd says, just log back in after buying the ticket and change your seat assignment to the EC seat you want. No need to call Delta reservation. Just an website bug that can be worked around.
That is the exact thing I did, however, in my case it still would not let me select EC even
after the ticket had been issued.