If you were dealing with an offshore retention agent, they don't give a hoot, nor have access to the best discounts. If you're dealing with a UK retention agent, then simply saying "I'll leave" won't necessarily trigger a better offer, because everybody says that. The agent does this job day in day out, and they've been trained to spot and react to specific cues, and to work out with reasonable accuracy when somebody is "just saying it". And they're paid bonuses to retain customers at the lowest cost, rather than being rewarded for simply handing out discounts. Whilst not quite the same starting point there's some thoughts in the link below which might be useful, but ultimately your only guarantee of a good deal is to be willing to follow through and cancel, and take a deal from somebody else. Potentially you'll get an outbound retention call offering a much better deal from VM after you've issued your 30 day notice, but you can't rely on that. Try and avoid taking any retentions call in the first ten-twelve days of your notice period, as the closer to the cancellation date you move, generally they offer better terms. If the call comes (again, don't bank on it), and the deal is worth having, then make sure you confirm all details (price, package content, if a discount the duration). If you can, push for a fixed price deal rather than a discount - if it is agreed as fixed price then VM can't raid your wallet with the frequent inflation busting price rises during the fixed term, whereas with a set discount they can. And should you take the VM deal, you then simply cancel the new installation that you'd have been wise to get tee'd up beforehand in case you don't get an acceptable offer from VM.