You need the TV Faults option when dialling 150 from your Virgin landline, or 0345 454 1111, but best to call at 8am to avoid call queues
You could try the text messaging service. Just send a text with a description of new remote 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.
Since you have posted in the V6 forum you could download the TV Control app which works on that box and use that until you receive a replacement remote