Mustafa, seven, and Muzzammel, five, are just two kids at mercy of the Taliban
Their father Adbul, 35, risked his life for UK as an interpreter, making him a target
Adbul came to UK with his son Shakeel, 15, in 2015 after being granted sanctuary
He is separated from wife and sons despite Government promise to reunite them
Ministers pledged two years ago - but at least 100 children and wives left behind