Samsung Mobile — Trying to void my warranty

Address:

Kolkata, West Bengal

Hello Sir, i had visited the samsung service center 27/06/15, i was facing the problem with wifi, i had submitted the mobile they told me to wait because they had to check software and hardware problem in the phone, i was waiting for 2 hours after that the guy sidhart told me that there is a problem in motherboard we will change the motherboard, Motherboard is not available now it will come by monday 29/06/15 & sorry for the delay they took time to open and check the mobile that was physical damage or not thats why we took 2 hours this is high end mobile take time to disemble. On 29/0615 when i had called him regarding my mobile they told me sorry you have to pay the money because this is water damage. How it can be possible, i use my mobile in very high protection case and the problem is in wifi only no wear and tear mark, they had checked for 2 hours completely then he accpeted for motherboard replacement so how can he change the sentence, I am attaching the job sheet with all the details and signature of the employee in a job sheet nowhere is mentioned any physical / Water damage . Please hep me to resolve my issue