Hi Becks I did basically what Andrew did at the supermarket when I was about 5.
I asked if I could have a chocolate bar, mum said no, I didn't think that was fair so I smuggled it. I had absolutely no idea or thought to it costing someone else, no idea of money value or anything.
Mum caught me out at the car (I looked terribly guilty and had it hidden under my coat). She marched me to the manager, got me to apologise, and left the bar there. Of course it wasn't opened so there was no money issue. Apparently (I don't remember this bit) the manager was going to say something like "oh that's ok, you can have it this time" but mum insisted that it stay there so I would learn. I never nicked anything again (except out of mum and dad's cupboards
).
Even though Andrew is younger than I was then, I still think returning and saying sorry is very important for the child to learn - consequences really. And perhaps even if you have to pay for another Kinder Surprise, you could still leave it at the supermarket (they can chuck it in the bin) and reiterate to Andrew that "mum told you that you can't have a chocolate today, we are leaving it at the supermarket because it was naughty to take it" etc.