Upvote:2
Virgin Atlantic have to refund you the airport taxes.
And no, a Schengen short-stay visa is not enough to transit a UK airport without a visa. You will be denied Boarding in Amsterdam if you try.
The people who did transit successfully must have had a visa/residence permit of Australia, Canada, New Zealand or the US, or a Schengen long-stay visa or residence permit, or possibly the check-in staff missed the visa requirement (which they can be heavily fined for)