O2 Volt Benefits no double data.

I signed up to M250 Boosted to M350 about a month ago, checked my O2 data last week which reset after a month, thus only shows 5gb data which it’ll use up quick. I signed up for £6 month 6gb data which it’ll use thought would be doubled. I checked after sim was activated, it was not doubled and realised £6 you get 3gb doubled to 6gb. That’s not enough for me so I rang virgin who the put me through to o2 and asked for the £10 month 10gb option, which is 5gb and should be doubled to 10gb. 
O2 say I don’t qualify and Virgin say they are going to deal with within 24 hours.