A bit confused about ESA Premiums

Hi just wondered if anybody knows to get the enhanced disability premium paid in ESA do you automatically get it added if 1. you are in the main phase? 2. On contribution based? 3. In the support group?

My hubby was migrated from I.B, had his Atos Medical, was found well enough to be in the WRAG, we wrote to ask them to explain how they came to the decision and they replied that they'd overturned the decision and he was placed in the support group.

I don't think we have a premium added, just wondered about who qualifies for it?

Thanks.