Have you tried contacting the regrades team? They can look at your current package and pricing and see what they can offer you.
You could try the text messaging service. Just send a text with a description of regrade 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, options 1,1 and 4 (Changes to your package) 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