Instacart order not delivered to me

The app showed order delivered but I didn't receive it. The shopper left a picture which I assume shall be a picture of delivery but the picture is totally black (cannot identify anything in the picture). I contacted Instacart customer service, and I was asked to file an appeal form. So far I haven't received any response about it from Instacart after more than one week though I was told that I would get a response between 24 hours to one week. Contacted Instacart again but got nothing except letting me wait. Anyone has similar experiences? How to deal with it? I used Instacart gift card (I suppose I can dispute if paying with credit card). It is unfair that Instacart user has to pay for the undelivered order.