http://worldoftanks.com/en/news/19/premium-vehicle-recovery-tool/
You can restore sold premium and gift tanks….for a price:
Along with this service, we’re introducing a new policy on the restoration of Premium vehicles. You’ll have 72 hours to restore any accidentally-sold Premium vehicle. This process can be completed for an unlimited number of vehicles, provided timely use of the tool. You can also restore any number of unique, gift vehicles one time every 180 days per vehicle.