MIXIT channels missing
Sky crime is no longer working. I can't view a recording from a few days ago.
Also can't find Aircraft investigation, Aussie gold hunters and Outback opal hunters.
I think you've worked it out. Whenever you change package, any elements of your contract that are legacy must be moved to the current equivalent.
Maxit is a legacy top-tier package which has been replaced with Mega-TV, substantially the same except for TNT Sports & some ITV-X bits. Mixit-TV is broadly Freeview-equivalent, and that would explain your issues with Sky Crime HD.
Check the table at the bottom of this page for reference - https://www.virginmedia.com/virgin-tv-edit/tips-and-tricks/virgin-tv-channel-guide
All distance sales - VM TV package changes included - come with statutory 14days "change of mind" right of return. Sounds like you need to compare the packages and potentially back your new contract out in order to renegotiate a new package that suits your needs.