Depending on the size of Costa’s scheme, and assuming you have a by-law based on the model by-laws attached to the NSW Strata Management Act, it may be possible to handle the matter at arm’s length by getting a circular out to all residents reminding them of the relevant by-law, with emphasis on the provision
(3) An owner or occupier of a lot must:
(a) comply with the local council’s requirements for the storage, handling and collection of garbage, waste and recyclable material, and
(b) notify the local council of any loss of, or damage to, receptacles provided by the local council for garbage, recyclable material or waste.
My local council in Sydney’s east explicitly excludes foam packing blocks and containers from its list of recyclables even if they are branded with the appropriate triangle marks. There may also be regulations about including trade waste in general garbage.
I appreciate that this may be oversimplifying matters; Costa has my sympathy. On the confidentiality issue, the managing agent presumably needs to use the content of the e-mail to be able to progress the complaint. If it comes to the point of issuing a Notice to Comply and then proceeding to a complaint to NCAT in the event of non-compliance, the requirement for mediation could be a real problem in terms of identity protection.