Ironically I've been trying to contact them for three days - initially I just wanted to renew the contract for another 18 months but they won't let you so they force you into a contract price being DOUBLED if you can't get through.
Cancelling your direct debit is not a good idea. All it will do is initiate VM's debt collection processes (which is a part of the company that works very efficiently). At the end of that proces it can result in missed payment charges, a trashed credit history and contact from debt collectors.
If you simply wish to cancel, with no further negotiation or discussion with VM …
You can cancel your services by post as per info below
https://www.virginmedia.com/help/cancel-virgin-media
Use a first-class, signed-for delivery service. This will give you a date/time of delivery when you gave VM your 30 days’ notice to cancel. Also keep a record of the tracking number.
If you cancel during a minimum term period VM may charge you early disconnection fees.
You can share your unhappy cancellation experience with OFCOM.
They launched an investigation into VM on 13 July 2023 specifically into VM's cancellation and complaints processes.
https://www.ofcom.org.uk/about-ofcom/bulletins/enforcement-bulletin/open-cases/cw_01275
Case ref. no. and an email at the bottom of the above page or submit with same info via the contact form
https://ofcomforms.secure.force.com/formentry/SitesFormCCTMonitoring
Submitting information won't help your individual complaint but it will contribute to the OFCOM investigation and it sounds like your experience is directly relevant to the terms of reference of the investigation.
