Seller has an additional option to block message from blocked buyers. However, existing transaction are not subject to this block. That is if you try to contact the seller directly, from his store page, it won't go through, but if you go to your purchase history and select "contact seller" it will.
If you started "not as described return" seller has no option but to take it. If he does not respond after certain period of time you can ask ebay to step in and sort it out.
