Postnet stock kept since June 2020

In June 2020 I sent a parcel to Postnet Klerksdorp but the customers adress brought up Alberton so order was not collected because obviously customer was in Klerksdorp not Alberton. In order to get this to Klerksdorp I'd have to pay but it would be free to have it sent back to me at Postnet Kenilworth centre..... I'm still waiting it's April 2021 and every month I'm at Postnet Kenilworth, Postnet Alberton is trying to find my goods in storage.... I have already replaced my customers order but I'm not getting my stock back from Postnet..... Can they destroy the stock because it's probably expired and they can re-imburse me.