What if you found £650 on the floor - but you had also just lost £180 (for the headphones)Regards the fiver, whereas that is technically stealing too, there's a simple question of degree and of practicality. Most people would keep it and no-one would be prosecuted for doing so.
But the incorrect item cost £650. If you went into a shop and nicked £650 worth of stuff, you absolutely would get prosecuted and rightly so. Would you condone doing that?
I didn't call anyone a thieving **** btw.