Haven’t received parcel for 7 months and still waiting.

I ordered a package from an international business I have supported several times. But this time around the package was delivered in March at the Post Office already, and I haven’t received any sms saying I can come collect. It has now been 7 months. The post office ( Cape Town International Airport Post Office) are not answering any calls and when going to their branch, their sign says closed, but there are people inside. WHAT CAN I DO?