Hi Fiona... Dialogue is healthy
My advice is call in the experts (not touting for business as our books are full), as you say aff marketing is complex and Im not sure where or who's advice you have been listening too. I would call in two or three affiliates and your network account manager and a rep from Next, if you have not already done so.
To go from Top of the tree to the bottom... clearly something went wrong to cause such a back lash. Im sure I can speak for most people, that it's appreciated that you came here and commented.
Maybe affiliates can now come here and post how they think Next could improve, maybe use this op and turn this into a really positive thread?
So what would next need to do to turn things around?