Nope the seller is wrong.
You open a case for item not as described in the Resolution Centre, link at foot of most pages, and if the seller wants their item back, the case enforces them to pay for that fully tracked return postage.
Just a tip, if bought from a Chinese seller whose item location on the listing states UK, then don't be fobbed off that the item needs to be sent back to China, it doesn't, it gets sent back to wherever the item location stated on the listing ..... and here..... at the seller's expense.
