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Increase cutout on stone benchtop

Hi I want to change my old gas hob to electric but found that the cutout for the hob is slightly too small (475mm) and will need to be increased to accommodate a new hob (at least 480mm). The benchtop is stone. I don't know what type but when I bought the house, description said granite. Is it possible to increase the cutout? Timeframe, I'm assuming I would have to get a gas fitter to remove the gas hob and line first before getting the benchtop cut. I'm hoping to get this done in the next couple of weeks as well as buy an electric hob.