This is a great marketing scheme Taco Bell is running. The app customization features is updated periodically. They have an a la cart options where you can "Add" things. But when you substitute, it does NOT subtract anything off. My kids are always customizing their food as well as I because we're vegetarian and vegan. When my son takes a Taco and substitutes with things he likes it's a $3 Taco from a $1.39. Please update this feature, because you are ripping off your customers. The latest update is flawed as well. There is an option to keep your favorite customized items. Lately, when you add to cart it defaults to its original meal, which is causing a major issue, because last time I placed an order I had to throw away 4 items. It's a shame and disgrace to waste food.