Zepto refusing to accept that one item was missing in my last order

Zepto refusing to accept that one item was missing in my last order
I ordered groceries last night from an app called zepto, the delivery guy called me way before he came to the location, he was asking my address on the phone call, when he came near to my location he called me again and was telling me that he can’t find my location(the location was already provided on the app). he asked me to come out on the street and he made me wait. then he came and gave my order without any paper bag or sealed pack, one item was missing which was Cadbury perk chocolate, he said “he doesn’t know anything about it may be there were any mistake by the provider please write that issue on the app’s customer section”. so I did but zepto refuses to admit that the item was missing or didn’t came without any seal.