Lenovo — chargeable service under warranty period

Address:

Jaipur, Rajasthan, 302016

I have a network problem with my lenovo vibe k5 plus. When i go to service center they tell me for charges for servicing and tell me it's liquid problem in jack. But it's wrong no liquid problem in my phone. The dont want to accept that there is no liquid problem. They tell every second customer same thing. My phone under warranty period and i want to free service.