Compmaint agaist samsung sevice center

Dear Sir, Not satisfied with Samsung service. I have purchased Samsung 10+ on 24th June,19, which is fully water resistant phone. two weeks ago, i was charging my phone and during the charging my phone display is off and phone is not getting on . When i took the phone to Samsung service center they said that the phone volume button is damaged, which was slightly bend, and they said that we have to take the approval from Samsung. So I Deposited my phone to them under full warranty. next day we called them for status than they told us your phone would be repaired out of Warranty and you have to pay Rs 37000/. Please note that volume key is working properly and there is no any connection with above Problem. I have original bill and mobile is in warranty. Please suggest our next course of action Thanking You V C Agarwal