If you want to write a message so that any member of eBay can see it then post something on the eBay Community Forums, as there are thousands of eBay buyers and sellers who use the forums regularly and read posts submitted on these forums.
You don't state what your reason was for wishing to post a message where it could be seen by everybody, but if it was because you've been stitched up in relation to a purchase you made on eBay then it would be worth bearing in mind that you cannot name and shame on the eBay forums, as if you do then all information that identifies the person you are naming will be removed by the forum moderators and you will receive a warning in relation to the post. If, however, you want to post something for another reason - for example, if you want to know how you can set your account up to start selling on eBay - then post a message in the relevant section of the forums and you ought to receive a reply from quite a few people who could offer you some useful advice in relation to your query.
