Your claim against the retailer is under the Consumer Rights Act, rather than under the Consumer Contracts Regulations, since the item purchased was not 'as described'. (See my post here for an explanation of the separate rights:
http://www.theanswerbank.co.uk/Shopping/Question1450431.html ).
So you should not be left out of pocket. The retailer should either send you a pre-paid returns envelope/label and refund you the cost of the item (inc p&p) or, if you send the item back at your own expense, refund you the cost of the item and
both sets of p&p charges.
(You'll note that I've written 'the retailer', rather than 'Amazon', as most problems with purchases through the Amazon website seem to occur when buying from Amazon traders, rather than when buying directly from Amazon itself).