So you put item A in the shopping basket at £14.99 in Sept.
You didn't complete the order.
Then in December you completed the order using the items already in the shopping cart.
But the items where NOW on sale for £7.99
You have been charged £14.99
What did the checkout say when you agreed to pay and handed over the Credit Card details??
Is the NOW price of £7.99 correct or an error on the website?