good for your sister. my experience using food apps has been nothing but positive. on rare occasion something is missing and i report it and i get refunded.
also i think anyone who expects delivered food to be hot and ready to eat is entitled AF. you should expect to re-heat anything that takes more than 5 minutes to deliver, which would be most anything unless you're like 5 blocks from the restaurant.
i don't know what universe people are living in where their take out doesn't have to be re-heated. mine always does. the only food that i don't have to re-heat is when i'm in the restaurant. my burritos that i walk to to get take out are always cold when I get home less it's like 80 degrees out.