Nokia India — nokia 6.1 plus

I purchased my nokia 6.1 plus from flipkart on 8th nov, 18. It was good but on 23 dec, 18 it stopped working & didn't get start. I took the device to nokia care ambala they checked the device & estimate the amount of 2000 to repair. It was in warranty period but still i agreed to pay the charges, they gave me time of 7 days but after 7 days they told me the issue of motherboard & told me the charges of 8000 & gave me time of 15 days after 15 days they told me the charges 8500+18%gst & gave me time to wait for another 15 days. Yesterday when i visited to them they didn't repaired it yet. & said the parts are not delivered yet. They don't even show me the status of their order. I want help from you asap. Otherwise i will knock the door of customer court.