3 week old iPhone 4S screen not working properly and apple cant repair it even though it is under a 2 year warranty??

Hi! I am an 11 year old girl who loveeeeeeesss her phone and wouldn't do anything to break it as i need it to contact friends and go on instagram etc. so anyways I took my 3 week old iPhone 4S into apple today as the screen was black on the right side and had a bunch of weird lines through the screen so i made a genius bar appointment and they said that they could not do anything to repair or repalce it as it had 'water damage'!! IN 3 WEEKS a phone that i care so much about has got watr in it?!?!!?!? its crazy and i have not exposed it to ANY liquids or water in the short time that i owned it. I had a very protective speck case and it had absolutley NO scratches, dents and i hadnt dropped it once, except on my face while i was playig on it ahahah and anyways it was in PERFECT condion. I got it for christmas and birthday combined present and i was so thrilled and now i am devostaed because they wont do anything about it!! I have filed a warranty claim and everything and explained that it was covered under warranty for 2 years but they still wont repalce it. 😟 please help! anyone with the same issue please share your experiences below or if you have any advice for mr i'd rly like do know. thanks a bunch guys xx 🙂 p.s sorry for the horrible spelling and grammar i was in a rush 😕