Following the instructions on this page
www.finnair.com/fi/gb/finnair-plus-tier-match and sent the email on Feb 4. Got a reply on March 7th with the following:
Dear miamiflyer
We are sorry for the belated reply.
You are now on Finnair Plus Silver tier and your Finnair Plus -card will be sent out within a week.
Best wishes
Finnair Plc
Finnair Customer Care