What CC do you have? All I've ever had to do is say is that I want to file a chargeback because of purchases not received. I've named items and that's it. I've gotten my money back immediately and without problem.
I've been on both ends of a chargeback so I know how it works well enough. The burned of proof falls on the merchant. They get the chargeback claim and may dispute it if they wish by sumbtting proof. I've never heard of the customer having to submit proof UNLESS the merchant responds. The merchant must respond with proof of delivery and guess what? CCK (nor BTL, lately) has proof of delivery.
I meant to say "the burden of proof falls on the merchant".