Bad bad service

after 3 months that i hade my phone it I couldn't hear the person on the other side so I took it back to the shop and after 3 times repairs they told me that the phone got water damage. Now they do not want to give me a new phone. And the guy who repairs my phone said its not my fault it is the phone it self, every time it heats up and cool down it gets damp and that causes the water damage. Still they do not want to give me a phone now I'm going to stop my debit order till they give me a new phone.