You could try the text messaging service. Just send a text with a description of 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, but best to call between 8am and 10am, or late afternoon around tea time to avoid call queues
Or write to them to as per the terms and conditions. If writing send it by registered post.
Thankyou for all your help staying with virgin they reduced my price to £29 for same package 18month contract
Just read your new contract carefully, if the £29 is a base price plus discount then although you discount can't decrease, the base price can still increase, so your price can still go up in that case!