Do your homework first and price up similar deals with other providers. Also determine what you actually need from VM. Do you need the current level of speed? Also look at if you need a new sim. VM now have the Volt packages which double your data and broadband speed, so it might be worthwhile taking out a lower broadband speed on a Volt bundle which would double your broadband speed .
When you decide to renegotiate/cancel the best method and time to contact them is to call 150 from a Virgin landline or mobile, or 0345 454 1111, but best to call at 8am when lines first open to avoid call queues.
Choose option 4 retentions (thinking of leaving us) They are generally based in the UK, and have a greater degree of knowledge and flexibility, along with a larger range of discounts than the front line agents. Hopefully you can negotiate a deal with them that's suitable to your pocket and needs in exchange for a new contract.
You can also speak to the team on WhatsApp on 0780 3089 684 but phone calls take priority.
You can also sign into My Virgin Media and click on Upgrade Offers to see if anything is available. Depending up staff availabilty there may also be a pop up messenger on that page so you can chat and discuss your options.