No response on query

My son sent me an important document from the USA on 28/12/2017. According to tracking document and number provided by the US Post Office , it arrived in SA on the 12th of January at tthe Jhb Int Airport (ORT Int Airport ) on 12 January 18 . It was delayed because of the storms at New York Airport. On the 18th of January it moved to the Int Mail Centre, and to Customes ion the same day. It carries the status of back at the Int Mail Centre since the 19th of January 2018. I am trying to track further progress and phoned their call centre number provided on the SAPO web page, they keep on advising that a email must be send to ********** which I did on 23/01/2018, as I am constantly being cut off by the call centre. There is no response aftyer two days from this e mail service. I need the documents urgently to finalise a transaction , and it the parcel carries the original documents, which had to be signed by my son in the USA. I stand to lose the transaction.