Identifying the Problem
People have been using main-chat frequently for their adverts although it is forbidden. If we think about the reason behind this action, I believe people do not find /ad system striking. It pops up for few seconds in our upper screen and vanishes. Therefore people use main-chat because it draws more attention.
Presenting a Solution
What I suggest to stop main-chat advertising is, we should create an application in our SAES Pad (M Tablet) called "Adverts". So people will make their advertisements there and then other players who are interested in buying something will simply check that application.
Usage of this application for advertisers should cost a fee. For example, you put your advert there and it stays there for 12 hours, which will cost 100K . The appearance of it must be simple to make it easy to use it.
I believe this'd stop main-chat advertisement and it would help alot in player-to-player sales.