sbiddle: I'm still totally lost here as to what this has to do with Telecom or why you think they should be responsible for collecting your details. Your relationship is with your telco. Is is their job to do this. Are they doing this now? I don't know because they're not my telco.
If you change your address you don't contact NZ post to change the billing address of every piece of mail you get. While they can provide a forwarding service it's up to you to contact businesses that you have a relationship with to update their details to ensure your mail is addressed correctly in the first place.
Steve I agree some great comments there that have changed my thinking over night.
Your NZPost comment is very valid I think. You are quite right that I don't expect NZ Post to tell all my mailers my new address and thinking that Telecom should do the same just because they answer the 111 telephone calls first, is silly as well.
The 111 agencies should set up an address system and provide an interface that members of the public can validate their address.
The system should be set up in such a way that service providers can, if they choose (with no obligation) provide this service to their customers.
As a member of the public, there should be a simple way for me to validate that the information held by the 111 service is correct.
Given how often telco providers make mistakes with information held in their systems, to expect them to store and pass the correct information is foolish on my part.