Don't forget a Hybrid car has 2 different systems on board, both of which require a major service at 4 years old.
When you think that a major service on a petrol or diesel car will need an engine oil and filter change, gearbox oil changed, brake fluid changed, spark plugs replaced, air and fuel filters replaced, as well as all the mechanicals checked, brakes, suspension, steering, electricals, tyres, hoses and belts, etc, etc.
All the above has to be done on a Hybrid car in addition to the EV checks, such as the high voltage and charging system checks, plus battery coolant change, and changing the coolant for electric motor all of which takes several hours of a man's time, I reckon we're looking at £500 in labour before adding the cost of parts and vat.