As a Lufthansa M&M Gold, I've always been able to assign and change my seats before travel with SAS. This time I booked through Opodo, but when i try to open my reservation through the SAS website with my PNR, it displays my reservation but not in an interactive way. So i couldn't even pay for a seat reservation.

A message tells me I need to speak to Opodo if i want to make any changes

So I only get to visualise my reservation online if I book through the SAS website, and get punished for using an OTA. Is that the way SAS works?