Damaged boxes and contents. Courier guy do not care

I sent a package, when it arrived at my client, the box was completely damaged and some of the contents were also damaged. I complained and they didn't even have the decency to get back to me. When I inquired again. I was told they are investigating. We are now 2 days past my last inquiry and they strill havent even bothered to get bak to me. They over charge on boxes making them bigger than they actually are so they charge you more. Big business that dont care about their customers at all its disgusting