Missed appointment

My daughter is claiming DLA and is being moved onto PIP. We were supposed to have been sent an appointment for a medical assessment which we did not receive. After calling the PIP team to find out the progress of her claim I was first told that a new appointment would be sent to us. The next thing was that we received a letter saying that her DLA was being stopped! I called them again and was told that a new appointment would not be issued but we would need a mandatory reconsideration and meanwhile DLA payments would be stopped.
There seems to be quite a lot involved in this; housing benefit, council tax benefit, road fund exemption as well as her ESA. Really worried!