If you've tried that and it's not working you can contact our BT Sport team on this link for help getting this sorted. Post back to let me know how you get on.
I tried every which way I could find - through MyBT & manage BT Sport, through the BTSport webpage, trying to watch one of the sport pack channels online & following the upgrade link... Same result every time & ended up going round in circles.
Am sorted now, phoned the on screen 0800 number this morning and everything up & running in 5 minutes 🙂