[BenMcr]

And all customers who took out the V+ between June 2007 and November 2007 paid £150 for the V+ installation.

Virgin could have just changed the price for the V+ boxes taken out after June 2007 and not offered existing customers any option to change.

I freely admit that the conversion fee is currently higher than the special offer install fee. However as soon as that ends it will be £50 less than the standard V+ install fee

If you don't want to pay the conversion fee, don't. Either carry on paying £10/£15 per month, or disconnect.