PIP Assesse

Hi I am looking for some advice if possible on Monday of this week I received a letter stating I needed to attend face to face appointment at a centre. I am housebound and do not leave my house due to my conditions. I did request a home visit when submitting PIP paperwork so when I called and explained this on Monday I was told my appointment would be cancelled and a new appointment given. Today Wednesday I have received 2 letters from Atos 1 stating an independent health professional has looked at my file and stated I would still have to attend a centre. I called them immediately and explained that by asking me to leave my house Atos are putting me in physical and mental danger - the woman stated I still have to attend and I could attend by taxi - there is no mention of that in the letter but she was adamant it was on her computer. I wont go into all my concerns but I am so stressed about having to leave my home to attend an external assessment it really has put me into panic situation and my pain is through the roof. If I dont attend they will I assume disallow my application is there anything else I can do? Atos also told me that whoever looked at my paperwork has deemed it that I dont have sufficient points for a home visit