sbiddle: Your phoneline is not on Chorus copper it's on the HFC network using their own copper and own Nortel switch.
I also don't understand why your price has gone up when there is no mention anywhere of $115 on the Vodafone website. The price listed is $109.99 with an extra $10 discount if you have an on account mobile.
Who knows the real reason for this change - this is what is stated on my bill (invoice date 11/12/2015) - just glad it is back to $109.99 :-)