I personally don't think offering discount contracts for specific services violates NN. As long as services are all accesibile at all time at the same speed, that's NN.

Whether it's free Spotify streaming or free Spotify membership or free iPhone offered with your contract (Vodafone UK does all three) ... They're all the same and nothing to do with NN in my mind.

As long as all data streams the same at all time. Everything else is just marketing and sale offers.