Phx770

So I got an avic 8200 nex almost a year ago and I am having issues with it. Whether in usb, sd, or bluetooth audio, I cannot skip to the previous track. The remote control is pretty useless other than changing source, volume, and skipping to next song. Also only the volume works on my steering wheel control. The place that installed it is full of idiots. That's a whole different topic though. Is this normal?