If you add TV to your existing package, you enter a new contract for that item. However, you could be missing out on discounts to your other services by doing it that way. I would seriously think about re-contracting the lot to get the cheapest prices.
Give Retentions a call on 150 Option 4 then 5. You might find it well worthwhile, & may get new broadband equipment in with the bargain.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV+), Talk Unlim Telco, VIVID 100, Virgin PAYG Mobile