I think they actually tick the boxes of things that they have done when they do it so that probably wasnt much
help
I just let them get on with mine when it came to it really so dont know exactly what they did apart from, Cambelt, Tensioners, Water Pump & 60,000 mile
Service
I think a lot of it was checks and changing if it needed it! IIRC i dont think they changed the plugs as i have had new ones since