Do you know modul which automatically add free product when customer have 3 products in cart?

[dotcompixel.com]

Hi,

 

I am looking for a module which automatically add the cheapest product to cart. I mean that customer add to cart 3 products from one category and the cheapest product will be free as a gift. 

 

I found out that Prestashop allow to set one free product after that customer add 3 products from same category but I need to have free cheapest product.

 

Do you know some modul which can do this?

 

Thanks for answer?