no one can know what would have happened. It can take less than a minute to steal a bike - even with a chain round. All you need is a van and two strong people to lift it in and it's gone.
unfortunately, there are less police on during the night, being as that most people are tucked up in bed, so if the police that are on are busy then they can't come and watch two people standing in yur drive!
You could try complaining but moped theft is very low dow on the list i would think. Sorry kathyan