Sapo lost my package

I parcel was sent from HK and was received and scanned in on the 02/07/2019. After a continuous emails and myself having to constantly contact the lady helping me i got no Joy. Now the person who sent the parcel from overseas has to write a formal form to request a trace? This is ridiculous and these were important documents which was sent as a high priority. Even the sender has not received the parcel back.

How will i take this further?