Volkswagen India — Vento/ABS light on in the display

I got my 2017 Vento serviced from VW authorised service centre KUN Volkswagen Bangalore South, Kanakapura Road, After few days I observed that the ABS and Traction Control lights are on in the display. I immediately called the service centre and they promised to pick the vehicle and get it checked. Next day the car was taken and I was called later and told that one of the sensors was faulty( as per their diagnostics) and they have cleaned and it does not show the indication in the display. Later when they were about to deliver the car they saw that the abs indication has again lit up. They said that they would need to replace the sensor on the rear right tyre and it costs 5000 Rs. I am not sure what the cost of a single tyre sensor is? For all 4 tyres it is 12000 Rs it seems. It seems like the prices are exaggerated.