As you can see, Stamf is doing sterling work.
As he says, you need to report it to your local police and get a crime number - the police can also put a mark against your reg.mark so that the car can be stopped and checked - so expect ANPR checks if they do.. Are you in London or elsewhere?
Also please post photos of your numberplate and car from the same sort of angles as the clearer ones Stamf has unearthed - members here seem to enjoy playing 'Spot the Difference'.
You might also check TfL for any outstanding PCNs against you reg.
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EDIT: post crossed with your latest.