The problem is that the VM pricing structure is designed to encourage customers to take more services. This means that you save little by dropping services and can sometimes end up paying more!!!
For example, the £5 monthly fee for the V+ is waived for XL TV customers, so that then becomes chargeable on if you downgrade your TV package. I don't even think that you can now go onto TV M with a V+ anymore, I believe the minimum package for V+ customers is now M+. Anybody?
I have looked on the website for you and this is the situation as I understand it:
The website says that the minimum broadband that you could now have of of 30Mb with XL phone costs £37.49 per month. If you were allowed to keep the free M TV service, you would be charged an extra £5 per month, making the total £42.49.
http://store.virginmedia.com/add-to-...art=BBXL60_PHM
I would advise you to look at the new "Collections" that include TiVo at no extra cost on any package, including TV size M, or to do as Andy has suggested
The cheapest Collection package is £40.99, but you would only get Talk Unlimited at weekends, but you would get TV M+.
http://store.virginmedia.com/add-to-...MP_TiVo500_PHM
If you customised this to have XL phone, the price becomes £48.99
http://store.virginmedia.com/add-to-...TIVO_ESSENTIAL