Hi, I recently called customer support and was quoted over £100 to upgrade from my old tivo 500gb box to the newest model, the current tivo is very slow, taking a long time to load iplayer and won't play prime video. As I've been a customer for many years I would of hope for a free upgrade. It would be cheaper for me just to switch providers.
Without having been party to the call you had, it's hard to comment in any detail.
Your best bet, assuming you are out of your minimum contractual period, is to have a look at your current package, and play around with the build a bundle checker to get an idea of current pricing. The site does give you "new customer" prices which you're not automatically entitled to, but also the standard prices, and perhaps looking at a figure somewhere between the two wouldn't be entirely unreasonable.
Then get a comparable price from any alternative suppliers that you're prepared to switch to, and call up Virgin Media Retentions with a view to re-contracting for 18months if you can agree a satisfactory price.. or giving your cancellation notice if not.