im not sure if this is the case with vauxhalls but on my old car - the members of the owners forum stated that the ECU could be reset.
simply unconnect the battery and tap the break pedal (to completely kill off power in the car)
wait for a minute or so and then reconnect. the onboard computer resets itself due to losing its power supply. once turned back on... the first few minutes of the engine being turned on is monitored by the ecu. this determines how your car drives for the future.
monitors things like how aggressive you are with your driving, ie if the engine monitors that it needs a lot of petrol to cope with fast speeds, then this becomes the default running style of the engine etc. they also said to do it after putting mods on a car, so that the car can work out how to run effectively
or something like that i cnt rly explain but does anyone know if this is tru