The portal recently got a coupon feature – you might even have some yourself. Pic from Ainheg:
http://rykoszet.info/wp-content/uploads/2017/02/jk5nj4gy9uhy.png
Check if you have any coupons here (only on the EU server, though):
https://eu.wargaming.net/shop/coupons/
Official response from WG regarding the coupons (source: Madlollipop):
Shame there won’t be more coupon waves in the near future. Most likely users who haven’t played WoT in a long while were the ones who recieved these.
