Terrible service

I couriered my ring to a business in Pretoria and when they received my parcel my ring was bend. It was perfectly normal when I delivered it to be couriered. Their service is terrible because they say it's not their problem and they won't and can't do anything about it. They damaged my valuable item and they don't want to take the blame. The employee that assisted me refuses to give his managers number so I can contact him.