"If the seller has done a thorough job with their description, there should be no excuse for a change of mind return" - just to add to what @papso22 has stated. When purchasing from a business seller online the buyer doesn't need to state a reason for the return of goods. Under the 'cooling off ' period granted to a buyer in the Consumer Rights Act they have a right to return for any reason, or no reason at all, for a minimum of 14 days after receipt.
The seller does have a right to expect the buyer to pay the return costs for a change of mind return providing it is stated in their returns policy.