As stated above, the Y stated on your BP is not the booking class; then your ticket would have been a very, very expensive economy ticket. You have to look at your itinerary/e-ticket receipt to see the actual booking class.
If you have already received the reply from SAS Retro-registr. that your outbound flights were not eligible for EuroBonus points, then you were booked in one of the non-earning SQ booking classes that you state above. Sorry, but there is nothing you can do and no reason to write more Eurobonus about this.
Apparently, your return flights have been in a higher booking class eligible for earning Eurobonus points. You should be happy for this.