Dear ClausJ,
We are very sorry for this misunderstanding.
It appears that you contacted, at first, our customer service for an exchange and not for the 14 days warranty.
Before you told us your product was opened, we accepted to make the exchange right away.
The fact that the product was opened made the exchange with another product impossible (we talked about mixing pieces of two different packs to get a brand new one, which was not possible since the pieces of those packs are different)
After we received your e-mail about the conditions of the 14 days warranty, that's when we understood