Miles booster for past flights?

Can I do Miles Booster on my recent flights (returned last week)?

If so, how? Do I have to call up or is there a way to do it online?

Thanks!

Yes you can do Miles Booster for flights taken in the past 6 months (and for the next week or so there's a 20% bonus).

And yes you can do it online. There's a link in the confirmation email you were sent when you booked (assuming you did so on the VS website).

there is also an extra bonus on boosts at the moment.
I x2 boosted my upcoming flight.