SA Post Office is terrible

I have been tracking a USPS package since 12 March, the last update on this package is that it departed OR Tambo to the destination in South Africa. So my parcel should be in South Africa and ready to collect. I have emailed the invoice as stated on their website, emailed all the email addresses and call the call centre and NOTHING HAPPENS!!!! This is the worst service on the entire planet!!! How do I find out what happened to the item????