help disable iconomy in essentials (spawning items with signs)

I'm running essentials and it seems to allow people to spawn items using only signs marked "buy" and I need help to disable this.

Seems they write [free] *Item* on a sign and then click the signs to get infinite amounts of the item

 

anyone?

Seriously this is ruining my server. ONE of you have to know what the hell is going on!

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Jesus fucking christ on a crutch my server is complete fucked over this exploit. Every single spawn has become blown to bits and covered in bedrock blocks and lava. SOMEONE HELP ME DISABLE THIS

 

Do I have to pay someone to get an answer here? Is disabling iconomy that complicated?

 

@Nathuram
You can ask in the Essentials thread or on their IRC channel. I'm not sure many people who frequent the general help threads will know that.