Where is my parcel???

My parcel was sent my by my mom from SA on the 2nd of March 2018 as priority mail to me in Cambridge Massachusetts, USA and to date I have not received my parcel. When phoning to find where my parcel is I was given three different departure dates on three different calls. The 19th, 16th, and then 15th of March. I’ve contacted the US post office they say they cannot even see that it has entered the United States. This is unacceptable, this cost a lot of money and was promised that it would be here in max 15 working days and there is still no sign of it. This is extremely urgent and I’ve sent two emails to your customer service to find out info and I have had no response. This is not priority mail at all! Please can somebody get back to me ASAP. Tracking number CN ********** 55ZA