As long as you are outside the minimum service period on your current contract then you should be able to negotiate a better deal. You need to call in and speak to VM to arrange a new deal and everybody gets a different deal as it is tailored for each customer and some people are eligible for loyalty discounts, some are not, so can't tell you exactly how much it would be for you. However, based on current non promo prices on the VM site then £55 per month should be the most you need to pay for the Big Kahuna package you are proposing.
A move to a current package will save you money. I was on an old package (might have been premier) a couple of years ago and when I spoke to the retentions team they couldn't offer me a better deal, until I pointed out I was on a legacy package that was costing more than the current Big Kahuna for identical services.
To get through to the retentions team you need to take the "Thinking of leaving us" options on the automated system when you call in.
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Scott
Disclaimer - I don't work for Virgin Media. I'm just another VM user trying to help out so my answers may be wrong :-) If you do like my answer please mark it as helpful as it may help others
My setup: Vivid 200 Optical fibre with Superhub 2 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.