Not sure - effectively was servicing the car at a different dealer than the one I bought it from who refused the service. Got in touch with the dealer I bought it from and waiting to hear back.
My friend had a JB4 on his car is Russia which I bought for him (along with some other sweet parts as warranty in Russia is much more relaxed) - he told me how it should be activated - but it didn't work so it definitely not it. The computer did throw the engine warning light couple of times before but restarting the did the trick.
To be fair I want to be prepared as much as possible before talking to these guys. The gearbox is not causing me much issues now but the last thing I would like to happen is having no warranty in case something else happens (my previous 335i had all 6 injectors replaced by warranty - guess it would've cost a small fortune otherwise). And obviously having the already identified problem fixed.