You can respond to a Building Notice of Intention / Development Control Order via email correspondence to the Council Building Compliance Officer who authored the letter.
Generally, you have two options, in so far as how to proceed:
Comply with the Development Control Order. Whether it be the demolition/rectification of the subject works or the ceasing of the use.
Lodgement of a Building Information Certificate (BIC). Should the works be permissible on your land, you can lodge a BIC for the regularisation of the subject works.
The BIC will be assessed by Council against the relevant planning controls applicable to your situation. Note that a BIC can only regularise unauthorised physical works and not an unauthorised use of a space. All applications for the use of a space, retrospective or otherwise, must be made via a Development Application. Lodgement of a BIC can be a complex and time sensitive process. It is often pertinent to consult with a town planner with regard to the lodgement of a BIC and the specific requirements in the circumstances of your case.
The Corona Projects team has more than 25 years of experience with your local council, so can not only meet your needs, but make sure your BIC application process is smoothly executed.
Contact the Corona Projects team here for a town planner.
Read more about unauthorised building works here.