Bad service after damaged online delivery done

Worst service online order. Was delivered with the box open. Should have had 20 wall panels in and only 18 in the box. After calling the so-called client services line and spoke to 5 different agents, I was placed on hold and cut off each time. No managers are available. You get a reference nr only on requesting it and told you will get an answer in 72 working hours in other words 9 days. My order that was damaged and wrong was done in 2 days why does it take 9 days to deliver the missing 2 panels?