From their T&C's:
15. VIKING RIGHT TO CANCEL OR VARY
If:-
(a)
we are not able to supply any of the goods for genuine reasons beyond our control, for instance, because we did not have the goods in stock, or sufficient goods in stock to meet all our orders, and we are not able to obtain the goods from our suppliers at all or in time to meet the delivery timescales; or
(b)
our web site and/or ordering web pages contained any error, including in relation to the description or price of any of the goods; or
(c)
if any of the goods are not in stock or insufficient goods are in stock to meet all our orders and cost of acquiring the goods to supply to you is higher than when your order was submitted or the cost of delivery is higher than when your order was submitted,
we shall be entitled to cancel the contract as a whole or in respect of those goods, in which case we will offer you a full refund, and we may also at the same time give you an offer to continue with your order subject to variations, or give an alternative offer, in which case we will identifying any changes to the goods, the price and delivery charges, and delivery timescales, and we will state how long that offer will remain open. These will be your only remedies and claims against us in such circumstances.