DS issues (Sound and wi-fi)?

Several weeks ago I was playing Pokemon Black and I beat Alder. I got into a fight with an Audino afterwards and the music was funny. Turns out the left hand speaker won't work a lot of the time so I can only hear everything on the right hand side. Also, several weeks ago I tried to get into the GTS to check my trade and I couldn't. Later, after playing Platinum a bit the GTS worked again and I got my new Braviary. Now the Wi-fi won't work again. I want to try for a Minun but I can't! The DS in question is a mettallic rose DS lite, about three years old, fair condition apart from a slightly sticky L key and some scratches. What should I do? Both my sisters managed to break their DS lites and have them sent to Nintendo for repairs, I don't want to anger my Dad by telling him my DS is tempermental...