You need to remember Telecom gave the proverbial finger to ISP's that rolled out LLU gear with wholesale "loyalty" pricing to ISP's that didn't. I'm not sure if that is still in effect now, maybe someone else here knows?
Wholesale Loyalty discounts where withdrawn.
I believe there is an NBR, Stuff and NZ Herald article some where on this/
Also, those prices above, some of them include POT's, while others are nDSL.