Samsung — unnecessary demand of money

Purchased a brand new samsung galaxy s5 mobile phone from a samsung outlet on 25th of july 2014 and the phone was not being charged from 16th of august 2014. i contacted the service station of samsung and an engineer visited my home. he said that the phone has got moisture in it and took it with him. After 4-5 days they are now asking INR 4000 just to open the phone and detect the problem even when it is within the warranty period. i am sure that i have not put any water or moisture in the phone but the company has put allegations on me that i have. please take some strict action against this as my business is suffering and i am occuring heavy losses.