You can text VM on 0753 305 1809 or get the WhatsApp number by logging into your online account via a mobile handset and there should be a link to speak to VM by WhatsApp. Neither service offers instant replies, so any negotiation can take days.
As an aside, it's laughable that you need to login via a mobile device to get the Whatsapp number - why can't these idiots just publish it? Why can't they be like other companies and have all aspects of account management through an easy to use customer web interface? Why can't they have helpful, well trained, UK based competent staff answer their phones? My car insurer (Privilege) offers full online management, and excellent UK based contact centres, every dealing I've ever had with them has left me thinking how friendly, helpful and competent their staff were. And that's for a contract that's a third the value of the amount I spend with VM. If they can do it, why not VM?
I suspect none of this is the sort of customer experience you want, but if you renew your contract with VM then you're telling them that this level of service is absolutely OK with you. My heart sinks any time I have to contact the company, it is without doubt the worst customer experience I've ever encountered, and things don't improve if you try and complain. In this day and age there's no excuse for customers not being able to change package (including renegotiating and cancelling) online, but VM's poor quality management are unfortunately only able to comprehend a world of low pay contact centres with crudely bolted on chat and Whatsapp capability, and the appalling unhelpful website makes things worse not better. Day after day we read posts here about VM's poor service, about the difficulty of quickly speaking to anybody able and willing to understand and resolve simple requests or problems. As I've written here before, the company's strapline ought to be "Virgin Media, where customer service comes to die".
