SEF - Document not received

I was supposed to receive my document from SEF and after waiting for few months I contacted SEF for not receiving my document yet. They said my document was sent on September 2 already and after I mentioned them I have not received it yet I got document tracking number and presented it to CTT. But, CTT says my document has been already delivered to my address. So, I checked through all boxes and letters and even asked my colleagues whether they received something of mine but it was nowhere to be found. Again, hoping delivery person might have mistakenly put my document in wrong box I requested nearby neighbors to check if there is something related to me but there was nothing. But, found out that so many letters were put in wrong boxes by CTT delivery person and may be in the similar way my important document might have been also delivered to wrong box or address. So, I would like to complain about some careless/negligence behaviors of CTT delivery person for loosing or misplacing our important documents.