We had a kiosk-type system at a computer repair shop where I worked where if we were super busy the customer could enter the make and model of the computer along with what the complaint was and their name and phone number and leave it on the counter for us to intake later.
We caught several people bringing in a different computer later trying to claim it was the same one and we owed them a "warranty repair" because we failed to fix it the first time.
Instead of modifying the kiosk application to require a serial number, the owner did away with it altogether and one of us from then on would have to drop what we were doing and intake all computers manually.
I suggested we could have text on the screen to the effect of "Attempting to obtain a repair under false pretenses is theft of services" or some such but he wouldn't have it.
So I guess the way we dealt with "fraud in our app" was that we stopped using the app.
