Damaged shoe box was sent to me and im being accused of damaging it

I purchased a chuck taylor takkies from the online store for an under privaledged child. After placing the order i spoke to his mum and relised i ordered a size too small so immediately called back for an exchange. I was informed that i cannot cancel my order i need to wait for it to come and then request a refund. When it came i opened the courier box and noticed the takkies box damaged. it didnt bother me because i knew it was going straight back. After sending it back i receive an email that it cannot be returned because the package is damaged!!!. I told them to look at the cameras in the warehouse where the item was packaged you will see it was packed as is but the agents are not harmful at all. Its not my fault i want me refund. order no. ***