Cab cost of Darjeeling-Gangtok-Lachung (6 day trip)

We are travelling to Darjeeling-Gangtok-Lachung from 2nd May-9th May. Please find our itinerary below. The cab driver we contacted has quoted 40,500 INR excluding Zero Point and Mt. Katao.

3rd May- NJP to Darjeeling 4th May- Darjeeling Local sightseeing 5th May- Darjeeling to Gangtok transfer 6th May- Gangtok to Lachung transfer 7th May- Lachung local sightseeing (Yumthang, Zero Point, Mt. Katao) 8th May- Lachung to Gangtok transfer 9th May- Gangtok to NJP transfer

Do you think the 40,500 INR is justified? We are 4 people and the driver is providing Innova. Also, the he will charge 3,500 INR per location for Zero Point and Mt. Katao. I feel it is too high. However, your views will definitely help as this is our first time to these places.