ESA Support Group F2F Assessment

I was invited to attend a Face to Face last week, after receiving a letter previously that was on the same date that I had written on the ESA50 as being unable to attend due to a hospital appointment. On changing the appointment 4 letters arrived one on the day which I never booked. I visited the assessment centre checked in but the waiting room was full of people with no one being called for an assessment. After waiting 55 mins I enquired if there was a delay I was told that they were running late. After 85mins I asked if my appointment would be honoured as a lady emerged from the room with an assessor stating that she had being called for 3 appointments only to be told they had over booked. She told the staff not to book her in until after Christmas. I was told I could book for another date, but enquired how long the wait was. We were told an hour. We asked if we could leave the centre to get some fresh air. They took my number in case the hour changed. We arrived back, 20 mins later the alert for parking pinged. We asked if I would be seen, as the parking was due to be renewed. I was told I was next 25 mins later I was called and told I wouldn't be seen. Could I rebook giving me the 21st Dec, I asked for after the Christmas period as the traffic that morning took 120mins in London traffic I was told it had to be in the month. Yet I heard others who arrived after me that day being offered Jan or Feb.
Today I received a letter for the 22nd Dec F2F.
Two Questions
1. What is my stance considering my condition sitting in a car if I have bowel accident with no toilet to access if delayed in traffic in Christmas shoppers madness.

2. The last assessor I had twice in a row, she noted incorrect information on the file re me and my condition. She yanked my leg and unravelled all the work done by my physio that the pain kept me awake that night and for several days after.
When I saw her last year she removed me from SG to WRAG, where I had to go through a Tribunal and I won.
If I am unlucky to get this woman again, after she pulled what seemed like a private note book on me when I saw her last year and took SG from me. Can I refuse to have her assess me following her incorrect log of me ( especially as I am under a neurologist and knee surgeon) and the stress and anguish she caused putting me through a Tribunal and those months of losing financially which put me in to arrears with my rent.
Please can you advise me as this fiasco has had me losing sleep since the envelope with the appointment as I don't see it as fair that others who arrived for seconds were offered Jan or Feb.
Thanking you in advance

Many thanks Gordon,

Its ok to move the new letter that arrived today this can be viewed as a new request ?

I did complain on my tribunal documentation and when I had the second assessment she asked if I was ok with her doing assessment for a second time.