I need help for coming up with an idea of a new product or service in an existing company or brand.

Answer 1

How about different companies (including banks) letting us know instantly when fraudulent use of our accounts, credit cards, etc., shows up?

Answer 2

This is how all those new flavors are invented in Blue Bell ice cream. Somebody has an idea. Most of them stink, but a few stick around, as in my favorite Cherry, or Mint chocolate.

I am fairly certain you can think of new variations on old products.