Kempis, you are right, if you fly with a D ticket, you sit in Ecco (or Ecco Plus if you are lucky) but the miles should be Business (double the Ecco milage) as you paid Business and just because UA does not offer business you should not be punished.

SK confirmed, that with D you get Business miles, but the computer did not do it automaticly, so they needed to correct it manualy.

When on a C ticket you fly First on UA and than you get also double points (First/Business is the same for SK in that Case).

Fact is, you should check that you get double miles when flying C or D.