Refuse to refund me for missing item!

I have always had good experiences with Superbalist until now. They delivered an order to me with 1 item missing from the order. I informed them of the missing item a few weeks ago and have not been getting responses unless I follow up with them. It's been weeks later and they are still "investigating"! They keep asking me the same questions over and over again and it's highly frustrating! I've paid for an item which I did not receive! It's simple as that. I want my money back! I'll never be shopping on Superbalist ever again after this experience.