ACS + Australia Post issue: ACS letter missed - Plz Help

Hi Friends,

Currently, I am in Dubai and 3 months back I applied for skilled assessment for Australian Immigration from ACS.

ACS sent me email on 6th June for the dispatchment of letter but still I didn't get it ...as per ACS they aren't responsible for delivery of letter once its out from ACS office ... ACS sent it through Australia Post (AU Post) ... As per AU Post it has been dispatched from Australia ...AU Post delevier it in UAE via Emirates Post .... As per Emirates Post they didn't receive letter in Dubai Office .... and may be it has been stuck on Dubai Customs due to clearance reasons with other shipment ... to track this shipment Dubai Customs need BOL (Bill of Lading document) from AU Post ... when I asked them they refused to share that information due to security reasons. AU Post suggested me to ask ACS to directly contact with AU Post to investigate the missing letter issue but ACS is not replying to me on this suggestion... earlier, ACS told me I should apply for replacement ACS letter...even If I apply again for replacement letter ... I doubt it may happen again

Please suggest what should I do now to get ACS letter? Is there any authority in Australia who can look into this?