I don't know about France, but in USA, a deal is not binding unless there is consideration on both sides of the deal. In other words, both parties (you and Nokia) have to give each other something of value. If you gave them $0 and they gave you a $500 tablet, the deal is only valid as long as both sides agree it is. However, if you gave them even $1 then it is valid regardless of whether Nokia thinks it is or not.