MM judgement just had a letter and I just don't get it.

Ok so for the past year I have been calling the so called pip helpline in regards to this issue. But before I even made the first call to them I spoke to an advisor at the c.a.b and this was also the same advisor who had helped me to fill out forms and actually get pip. I was awarded standard rate and this was for mental health and anxiety issues not for my physical problems as I had been told I could not claim pip for this. However I later found out this was untrue and I could have actually claimed for physical. So anyway I went to the assessment and I passed first time the assessor was a nasty piece of work and had me in tears and a shaking wreck for weeks afterwards I was tormented by nightmares and bad self harming episodes. But even she as horrible as she was admitted I had the issues I had said and I needed support in social situations blah blah blah. She wrote this down in her report about me. So my c.a.b advisor said to me yes you are affected by the mm judgement and even better the assessor has admitted that she agrees this is the case. He told me to give them a call and let them know and also to be willing to send out any proof of this to them. I keep all of my letters from DWP as well as hospital letters and doctors letters reports ect. Some of which actually go back years. So I did what he said and I gave them a call the person I spoke to told me to send out copies of the letters I had because it sounded as though I was affected by this. So I did what he said and I have never received a letter of a call to tell me I have been awarded this backdated money. But for the past twelve months I have been told by numerous people I have spoken to at the pip helpline that yes I have been affected by the mm judgement and I have been selected they was just waiting for a case manager to look things over and then I would be contacted about when I can expect to receive a payment. So today I got a nasty shock because they have sent me two letters out both exactly the same and they tell me I will not be receiving any back payment. And the reason they give is because even though they acknowledge I need prompting social support ect it is not by a professional it is my own son that helps me. So because it is a member of my own family I am not entitled to a penny. What I don't understand is why did they not tell me this at the beginning because they knew this already so why did they string me along on the phonecalls. I even had one person I spoke to three months ago telling me it was good news for me because I would definitely receive a payment because I fall into the correct category. Why do they lie to people like this it's infuriating and I don't know what to do next. I don't think it's worth even calling them because they will probably tell more lies and I may lose my award completely.