Unfortunately you need to contact VM directly as the Forum Team don't have access to enable them to change your package or cancel your account.
You can negotiate a new package with both the regrades and retentions (cancellation) teams, however only retentions can cancel your account.
You could try the text messaging service. Just send a text with a description of regrade (or cancellation) to 07533 051809. Your message will go into a queue and a representative will respond to you as soon as possible. It may take a few days.
You can also call 150 from your Virgin landline, or 0345 454 1111, butbest to call at 8am to avoid call queues
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali