Is a restocking fee legal under the Distance Selling Regulations?

I purchased an item via an Amazon trader. Under the Distance Selling Regulations I have seven days to return the item and receive a refund if I change my mind, as long as the item is still in brand new condition with all the packaging intact. However, the Amazon trader intends to charge me a 10% restocking fee! Is this legal under the Distance Selling Regulations that we have in the UK?