Received really damaged parcel

My mom sent down a sewing machine from Postnet in Middelburg Mpumalanga, to Herm**** western Cape, she paid for insurance aswell because it is a sentimental item. When we received the sewing machine and opened the box at home, it was lying sideways had a huge crack in the cover and a piece of the hard plastic on the machine itself was broken off. Definitely happened from it being dropped as it is quite heavy! I'm very upset and honestly they were my first option for courier service. Now I wish I'd used someone else. I have no idea who to contact regarding this.