I had a separate issue with Virgin where the terms of their voucher policy appears to be "use it or lose it" in terms of value. I had a voucher for myself and my girlfriend worth £2,000. I was told by Virgin that if I booked flights worth £1,500 I would just lose the additional £500 which seems very unfair to me. Other airlines (e.g. BA) give you a voucher for the total and you can chip away at it until you've used the full credit. Not with Virgin it seems - their response to my query questioning this policy is below
"It goes without saying how sorry I am to learn that you’ve been left feeling so let down by our policy relating to the use of travel vouchers. I assure you it would never be our intention to cause any upset.
Our Customer Services department are best placed to deal with your query as they will be able to look at options to try and utilise the full cost of the voucher. This could mean looking to upgrade you to our Premium cabin if Upper Class is more than the value of the voucher.
I can see that you're unhappy with the policy. While we can't change this, you can be sure that your concerns have been taken into consideration and will be helpful in making changes in the future."
So basically I'm left looking to find a flight for as close to £2,000 as I can even if it involves travelling in say premium economy which I personally don't see the value of paying the extra compared to economy - and it is no-where near enough for 2 x upper class tickets.