Lack of service from SA Post Office

I got a notice to collect a parcel from the post office, put in the post box this week. I go to collect it and they've sent it back to sender (in australia) this week. The woman behind the counter said they only keep the parcels for a month then return them. Allegedly she sent emails which neither the sender nor myself ever got. The paper was stamped the 10/04/2025, but was only put in the post box this week. The woman behind the counter says its gone back to send and theres nothing she can do, I should have collected it before the month was up. Not sure how i was supposed to have collected something in time when the notication arrived this week?