Now that I look back at the updated flight info, there was a link to accept the changes. I missed this when it was sent. However the changes did not show the change from A3 to OA, rather just the change in flight number.

The more I look at the original information, the more I am confused what I originally booked. No mention of OA as the operating carrier in the booking info, but Checkmytrip.com (after the flight number change in September) shows A3 as the operating carrier while the app shows OA as the operating carrier. CMT had originally listed the flight as being operated by a Dash 8, which neither A3 or OA seems to operate (according to airfleets.net), although it now correctly shows the A320 that we used.

I will try to retrocredit the flights to SAS and see what happens. In worst case I will write to A3 and asked what happened, if only as I am curious to know.