Tata Motors — tata tiago - poor after sales service

Dear team
I have purchased tata tiago in may 2017. Since day 1 the rear door window is not working. During first service i was assured that spare part is not available, same thing was told during 2nd service last week on 7th nov 2017 at tathawade pune concorde service centre.
The crm tanvi and service advisor tukaram are totally clueless and have poor knowledge of vehicle. Even after escalating the issue, i'm not able to get resolution of my complain and it's giving me a very bad impression of customer service at tata motors as i opted for your car first time.

N khandelwal
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Car nbr mh12 pc1797