It is a requirement of a licence that, before performing work for a person or using parts not agreed to by a person in the estimate of work, the licensee must—
(a) explain to the person—
(i) what the additional work or part is; and
(ii) what the cost of the work or part is; and
(b) obtain the person's authorisation to—
(i) conduct the work or install the part; and
(ii) charge for the additional work or installation.