How serious or determined are you to cancel, hypothetically, if you get nowhere with any sort of negotiations? I take it your 18 month minimum term expires in October of this year, and all discounts expire?
What you certainly ‘could’ do, is firstly investigate and see what alternative suppliers are available to you and whether they would suit your needs. Then send a letter (keep a copy and send it signed-for receipt), to their Sunderland office address (details on the website under the ‘how to cancel’ section), and express you wish to cancel as of xyz date (allowing for the minimum 30 days notice period).
And now here starts the poker game. As long as you have allowed ‘marketing calls’ in your VM profile, there is a good chance that the outbound retentions staff will call you and offer a deal.* If they do, and you think it reasonable then you must accept it there and then, no ‘I’ll think about it and call you back' (whatever they may promise), doesn’t work like that. Otherwise, you reject it, and there is a slim chance that they may call you back and offer a better deal - but absolutely do not rely on it!
It’s all bluff and counter bluff, if VM don’t believe you will leave and cave in, they’ll offer you nothing, but, alternatively, they won’t offer you anything that isn't worth their while - they’d rather you leave than that! Forget what ‘new customers’ get, annoying as it may seem, you simply won’t get that deal or anything close, again, they’ll (probably) again, rather you leave than let you have that!
So do your homework, be absolutely prepared to go elsewhere, keep trying the helpline, you can’t really renegotiate a new deal via the website, only by using their ‘chat’ feature, but, judging from posts on here, that also seems to be in a similar state of abject collapse as the phone provision. But ultimately send in the letter.
