I've bought a washing machine which doesn't work. I've opened a return which was accepted. In the case I asked seller to arrange collection, but insead he's sent me a royal mail postage label. This is not going to be accepted by royal mail, it's too heavy for royal mail and parcelforce, he's a experienced seller so I'm sure he knows this. So I've and asked him again to arrange collection, in the same way it was delivered to me. He's gone quiet. Of course I've been given a deadline to return this item and if he doesn't respond I'm worried I'm going to be stuck with this item and hundreds of £s out of pocket. Any advice please?