Try calling up, selecting options for "about my account" and "thinking of leaving". Reports here suggest response times are massively variable from a couple of minutes to hours (with regular hourly disconnections), and that the response you'll get on trying to significantly reduce cost will be equally variable. When you make the call (inbound) the agents generally have less leeway than outbound call agents phoning you and trying to retain a customer who has cancelled and is in the 30 day notice period. Because retentions agents generally have a fixed discount budget in a given time period and a bonus based on tiered levels of customers retained, then there's no logic from your perspective to what they'll offer you - if they're already up to their maximum personal retention quota for the period, then there's no logic for them to offer you any discount, even though the agent next to them my be down on quota, and using their discount allowance very generously.
Looking at what's within your control, your leverage to getting a deal is the belief by the agent that you will be prepared to leave - not "loyalty" or how long you've been a customer. Don't be distracted by the agent prattling on about the VM speed advantage, or offered benefits that don't have a real cash value to you (eg a monthly SIM at no extra charge is of no value unless you've got another mobile deal you can cancel without penalty). Best bet is to arm yourself with knowledge of what competitors will offer you as a new customer say via Uswitch, MoneySupermarket, those meerkats etc, phone and offer your 30 days notice, and see what they come up with. If the phone experience is all too much, cancel VM by recorded post and order a different ISP for installation at the end of your VM contract, and wait and see if you get an outbound retention call, then review - either reject that, or cancel the new ISP. But if you really want to stay, don't blame me if you miss that VM call, or it is never made.....
