Hi jw98
I agree with Adduxi it may be best speaking to retentions. They have better offers than the front line agents. Although you might speak to a first line agent to begin with tell them you are wanting to speak to cancellations and they should then pass you through to the actual retentions agent.
Also, have you tried signing into https://www.virginmedia.com/my-virgin-media/ and clicking on "Upgrade package"? This may show you online offers currently available to yourself, or a link to a chat box to discuss a new package/contract.
Also check your marketing preferences within My Virgin Media as you that may be turned off, hence no emails.
My contract isn't due for renewal until November, however I've been receiving email offers for the past two months, so I suggest that you check your spam/junk folder in case any emails have been diverted there.