Most probably already know this but for those that still haven't logged in to the game (yes you MrB!):
After you have unlocked (with certs or Aur) something (a weapon add-on, vehicle add-on, weapon etc) you don't automatically spawn with them, first you need to add it to your loadout.
For instance, if you unlock the S-AMS ability on your Sunderer you need to go to your Sunderer loadout and in the Util tab activate the AMS button. In the same tab the other Sunderer unlocks like Ammo Supply and Repair will show up when you cert them.