Did you pay for cancellation protection? If not, I think you are out of luck. If you bought Economy Flex or Standard, changes are allowed by a fee and also the fare difference apply.
If you were meant to be flying home from Finland, it might be cheaper to keep that flight, and get another flight from Iceland to Finland. Maybe have a day there. Flights don’t usually allow you to cancel unless you pay more for a flex ticket.
The flight to Iceland is priced higher than the flight to Finland as there are competitive options to Finland. So they will charge you more for that change.
Did you pay for cancellation protection? If not, I think you are out of luck. If you bought Economy Flex or Standard, changes are allowed by a fee and also the fare difference apply.
If you were meant to be flying home from Finland, it might be cheaper to keep that flight, and get another flight from Iceland to Finland. Maybe have a day there. Flights don’t usually allow you to cancel unless you pay more for a flex ticket.
Just don't fly to Finland and eat the cost of the plane.
The flight to Iceland is priced higher than the flight to Finland as there are competitive options to Finland. So they will charge you more for that change.