Wholesale Merchandise Australia P/L

I bought 150 flat pack but rigid matte white magnetic flap boxes off them. They weren't cheap but that's okay because I wanted something durable for my business. I first got a sample and it was perfect- now it is hit and miss with the rest. Boxes won't even close/ shut as the boxes have been made uneven. I emailed them and was told it was my fault there was a week gap where I should have checked all 150 boxes? I leave them flat packed until I have an order so it keeps them looking new?! So now half the boxes I can't even use I just have to throw away... feel like I got taken advantage of as I'm new to this area!