Volume on iPhone 2g doesn't work!

[dethformybodom]

Ok so me and my dad drove somewhere and I saw a plug for iPods/iPhone go charge my iPhone(2g 3.1.2 with tmobile) so I plug it in it charges and says this accesory is not made for iPhone. Thought ok no problem it's an old radio. So we get to the place and I use the phone. Nothing wrong. We leave, I charge it once again. Now we get back home and it says this accesory is not made for iPhone, turn on airplane mode, blah blah blah. It says that like every 15 seconds. So I let it die. IT stops until like 70%. Then the message. It dies I turn it on and message show every 5 minutes maybe. Plug it into the dock, it starts messing up. Now the volume slider does t show on YouTube,iPod, or videos. Not even locking sounds, clicks or anything. Yet it works with voice recordings and calling. I plug in headphones and it works. Let it die. It works nothng wrong then it just happens, but the message doesn't appear so maybe I need it to wear off? I don't know so any advice is appreciated. Also I can't take it back, my mom is pissed it was about $150(came 2 headphones, 3 cables, and box)