Phone not Serviced or Changed in Warranty

I bought Nokia phone form flipkart. My invoice date is 8th Sep 2014. My phone stopped working with in a year and i went to nokia service center in kanpur and they have taken the phone for repair on 3th Sep 2015. IMEI code for repair is – 354237066631623. They are not repairing my phone saying that the bill is not correct.
I have my order confirmation email, the invoice and the receipt from Nokia center for receving my phone for repair. My phone had 1 yr warranty and as such i expect it to be repaired or replaced for its more than 3 months and after many follow ups they are now saying bill is incorrect. I am not getting why bill is incorrect and why my phone be repaired. Totally rejecting customer satisfaction here..