Hi Clive753,
There are only two channel tiers (packages) available Mixit and Mega. The Mega package includes more channels and is more expensive.
If you've just changed your contract and within the 14 day cooling off period then you can cancel the regrade and re-negotiate a new deal. You would need to speak to regrades for pricing.
You can however add the extra Kids channels to the Mixit offering for an additional £5 per month.
You can also add TNT Sports for the additional cost of £18 per month, or Sky Sports/Sky Cinema/Premier Sports for an additional monthy fee.
See https://www.virginmedia.com/the-edit/tv/virgin-tv-360-channel-guide