Again, they state this on their return page:
"if the buyer properly rejects any of the goods in accordance with the Distance Selling Regulations within 7 working days in writing, the Supplier shall nonetheless be responsible for the return cost of the goods."
So I was incorporating their policy and the DSR into one statement.
I think 'return cost' is implying the cost to them to restock the item in their store and handle it. Not that they should be paying the return shipping cost back to the buyer.
Very few online stores have a policy of refunding the buyer postage just because they don't like something or wish to return it under the Distance Selling Regs for whatever reason.
The exception to this is when an item is faulty or completely different to advertised. In that case, its pretty much expected that the retailer should refund all shipping costs for having wasted your time.
Again, its all about how you handle it though. Getting on your high horse quoting the law and demanding money back does nothing but annoy the retailer.