The £14.99 is a listing fee, which is non refundable, and payable sale or no sale, it's charged the second the item goes live.
It's the same if you placed your item in your local paper and it didn't sell, the paper would not refund you, your advertising fees.
Seller fees for the caravan if a cancellation is made citing ' Buyer Requests to Cancel' does refund you your selling fees .
@abiterry1981