If you believe that there is development occurring in your area without the necessary planning permission, you can submit an enforcement complaint to the local Council asking them to investigate. Each Council website should provide specific instructions on how to do so. In general, you will need to provide details of the location and development and/or activity in question. Providing photos, if possible, is often helpful as well. 

If you are unsure if the development is unauthorised, you can start by searching for it in the relevant planning authority database, which can be found on ePlans.