I have used Nectar partner offers on several occasions. Each time, the points are not added. When you are able to reach Nectar, they refer you to the partner organization who confirm that it is Nectar who need to add the points to your account. When you go back to Nectar, they have a **different** answer: that you didn't use their link correctly. Obviously you cannot prove this, especially if some time has passed.
Endless roundabout and just not worth the time and effort.