From Nestle themselves.

> No company sourcing cocoa from Côte d’Ivoire can guarantee they have completely removed the risk of children working on small farms in their supply chain. Nestlé is no different, but we are determined to tackle the problem.

http://www.nestle.com/ask-nestle/human-rights/answers/nestle...

They have been in business for years. If they wanted to stop in the past, they could, overnight. It would be expensive, but only because of their entrenched business model which they had a hand in establishing.