Cheated by authorised service center of karbonn mobile

&lt;p&gt;&lt;b&gt;Location/place&lt;/b&gt;: Pune&lt;/p&gt;<p><b>Name of company/service</b>: karbonn mobile</p>I was purchased karbonn mobile (model-A7) from kroma center, Pune.
Mobile was switched off due to water problem on 21.01.2013, so on 21.01.2013 i was handover that mobile at authorised service center of karbonn mobile, shivajinagar(Pune).
Service centers service person check the mobile & told us motherbord of mobile had problem you have to pay rupees 1500.00 for repairing & wait for 15 to 20 days.
Today i was at that service center for collecting mobile.Service centers person handover my mobile & told us this mobile is unrepairable.
Now i have following doubts.

1)Servive centers service person confirm the reason of mobile problem & ask for rupees then why this mobile is unrepairable.
That means in 15 to 20 days they are removed the parts of mobile.
2)What is warranty.
3)Karbobnn mobiles are not quality mobiles.
4)Poor service centers.

Now i have replacement of karbonn handset.