head unit gone crazy

I have a dual headunit in my 94 t/a with the flip down face, anyway when I put the face down and try to control the volume it will go up fine but when i turn the volume down the volume still goes up. The thing does it on the other settings like the bass and tremble<sp? too. It didnt do it for the first couple weeks I had it, whats wrong with it ?

thanks for lookin'

Its a dual, which basically means its broke and needs to be replaced

There's a reason why Dual equipment is so cheap. Looks like you're finding out why. If it isn't under warranty anymore I would recommend replacing it with an Alpine.