I had a similar experience. I went for a service and was told that it would cost me 18000. When I showed them the cost calculator charges were 8000, first they dismissed, then tried to reason with me and finally when I threatened to report this discrepancy to Skoda, they agreed to service it at the cost mentioned.
I second ypunjani211265 comments above. They are the worst Service providers. They surely treat customers as if they are fools. I needed to get my car serviced and I took and estimate using the 'Skoda Service Calculator' (which was approx Rs.6800/-) but when I reached the service station the estimate provided by them was more than double (Rs 14500/-). Would not recommend them to anyone.