This is just wrong
Question from Russell updated on 21st March 2011:
Our expert Jeff Montgomery responded:

The Residential Tenancies Act 1986 (the Act) applies only to the relationship between a tenant and landlord. It does not cover the relationship between a landlord and a property manager, or between a landlord and a debt collection agency.
You may wish to seek independent legal advice from a solicitor or your local community law centre if you have any concerns regarding costs you have incurred (or are still incurring) in relation to your arrangement with your property manager or Baycorp.
The Act has recently been amended to say that the Tenancy Tribunal may make an order for a tenant to reimburse the landlord for any reasonable costs the landlord has incurred in recovering any overdue payments (that a tenant owes as part of a Tenancy Tribunal order), where there is a specific clause in the tenancy agreement that allows this.
Unfortunately this may not assist the situation you have described as the amendment came into effect 1 October 2010. It may, however, assist you with any future tenancies.
To discuss your situation further, or for information about the recent amendments to the Act, you can visit the Department’s website (www.dbh.govt.nz), or call 0800 TENANCY (0800 836 262).
The Department of Building and Housing provides information and guidance on building law and compliance, services including weathertight homes, and advice for tenants and landlords.