Broken Cupboard Panel

I bought R7000 worth of self-assembly cupboards (Two cupboards, 2 top boxes and two desks) from Decofurn, invoice number FUR157981, and after trying to assemble each unit , I found that the last cupboard had one panel with a 60cm crack in the board. And now they don't want to replace the panel. There response was that I had to check and report any faults within 48 hours of receipt. How can you assemble those 6 units in 48 hours and check the all the pieces and hundreds of *****s and niknaks. ******