Complaint regarding Motorola service issue

I had purchase my mob from amazon on 20th March 2017. It was working fine but on 8th Aug it got hang and so i restart it. A phone was On but network issue was there. It was showing full network but some times i could make the calls and sometimes it was not getting connected. So i search for service center online so i got Lower parel address and shop name is TODAY TELECOM. I went there and told that there is a network issue. so they also check and told that it may be software problem, so they called me after hour. When i reach after 1 hr they handed me the handset and told that my problem is solved. But when i check it it was not solved. And there was no network as all. As when i had given them i was getting the network but when they handover the handset the network was total gone. So i bring it to their notice that there is no network at all. So again they told me to come after hour. So again when i reach after hour i was suprised, they told me that there is an hardware error and i had to pay Rs 1650 for the same. I told them that it is under warranty and why should i pay them for the same. They told me it is coz of water gone in the phone. I told them that my mob is packed and water cant go in the phone. So they told that coz of moisture or other reason it may be damage. As i came to know that i was getting fool by them. As i had observe that many of customer came there who has warranty are paying the charges for one or other reason. So this service center is only to make the money not to give service to the customers. As today they had called me to collect the mobile. So any one can help me and guide me what action can i take against them. As when i took my phone only network issue was there but after they do something total network was gone. So they had done some mistake and i had to pay for thier mistake. So what should i do. Please any one can help me with the suggestion of what action i can take against them.

Mahesh Shere
Mumbai 400031, Maharashtra
Email: sxxxxxxxxxp@yahoo.com