I'm an O2 and Virgin customer and I've signed up for the Volt benefits via My O2. O2 doubled my data allowance pretty quickly...but there has been no action on the Virgin side of things.
When I ask about it Virgin customer service want to upsell me to a new broadband package (I've spoken to a few people and both have tried it). They say that I'm not eligible for the Volt speed boost because of the "special" deal I'm on (I was a new customer 5 months ago - presumably they are talking about the reduced price for the first 18 months).
Interesting! The second person I spoke to was from the retention team but they couldn't help (apart from offering another upsell deal). They suggested waiting a bit longer to see what was available...which makes me think they just weren't aware of the Volt increase.
Sorry to hear of the problems getting the Volt benefits applied to your Virgin Media account. We aren't able to arrange this for you from here I'm afraid but if you contact the team using any of the methods here they will be happy to help.
We also have these helpful tips in regards to Volt.