Benefit claim turning into a nightmare

I was diagnosed with Autism in March after suffering from problems all my life and no one being able to figure out the reason. I was told at the time that I should be entitled to PIP given all the problems I face on a daily basis and how much help I require with simple tasks. So, I applied and went through the process even though I was apprehensive as filling out forms and having assessments were something I would rather do without. The whole process has been very upsetting and after 3 months and an appeal they are still claiming I am not entitled to anything and are scoring me 0 on absolutely everything and I am completely confused and upset by the whole thing. 

Firstly the assessment I had with their "health professional" was excruciating. Not only did it feel like she was trying to put words in my mouth the entire time and manipulate what I was saying to make it seem like I was fine, at the end of the interview she said "with all due respect you're a little old for an autism diagnosis" (I am 26). This was extremely upsetting to hear as I had just started to feel like I finally knew why I was different and why I had problems. Also I didn't think age mattered when it came to autism. She then proceeded to say "if I were you I would go down to the doctors and bang some drums it sounds like you are bipolar". I was so upset after this as I didn't see what that had to do with my claim and I don't see how it was her right to say. I still struggle with every day living as per the requirements but it seemed like she had completely disregarded all of that.

Then the first rejection letter came through and they had scored me 0 on anything and on their info about how they had come to their decision, everything written was either a complete fabrication e.g. saying that I appeared relaxed during my assessment and that I fully engaged and had no issue making eye contact (I don't see how that even matters to my claim but also I don't even know what the woman looked like as I didn't look at her once and it clearly states in my diagnostic assessment that eye contact is a big problem for me). So it was a complete lie, the rest was just twisting my words or repetition of the fact that I don't receive any treatment? Well I explained to her that I am waiting to receive an appointment with my counsellor to work out treatment but unfortunately its taking a long time. I also outlined all the treatment I had received in the past when I had no specific diagnosis, e.g anti depression/anxiety medications, CBT, counselling etc. but they had totally disregarded it. The list of inaccuracies goes on. 

I then appealed and wrote a long letter, quoting their letter and explaining why it was incorrect and how some of it was just plain lies. Then a week later I received an extremely similar rejection letter basically saying the same as before leading me to believe they hadn't even read my appeal. They stated I hadn't "specified" which parts I wished them to look at again when I went through it point by point?! Then on the end they just tagged on a load of jargon about me being physically capable... 

I am at a loss I know I have one more chance to appeal it but I am so upset by the whole process so far that I am just becoming depressed with it. I felt personally attacted by the "medical professional" they sent and it feels like everything I have said has been completely disregarded... 

Has anyone had a similar experience in applications for benefits or does any one have any advice? Perhaps it's something I'm doing wrong?