PIP reassessment lost mobility!

Hi I had a decision june 2014 for PIP transferred from DLA. I had been to tribunal in january 2014 because I was refused DLA and won life award Low Mobility. I suffer from ME, Agoraphobia, worn disc, etc.

The decision in June 2014 awarded me Standard Daily Living and nothing for Mobility (only scored 4 points for prompting, etc.) again I appealed and won Standard Living and Standard Mobility (10 points because I need someone with me) till June 2016.

I was reassessed in July, 2015 and received the decision notice on 14th August, 2015.

I have been awarded standard Care and nothing for mobility again (given 4 points this time for being able to stand and move unaided more than 50 meters but no more than 200 meters 4 points nothing for prompting) of course i'm going to ask for a mandatory reconsideration and have asked for the assessors report, they've told me I should get this in 10 days today after being told last week that it was sent within 5 days.

Anyway the only dates in the decision letter state that the award of Standard Living is from the 12th August, 2015.
I received letters from Council regarding my HB and have been told by them that the DWP have told them that my award has been backdated to June 2014.

Surely they cant do this, your views and advice as to what I should do please.

Thanks Gordon. Hoping I dont have to go to tribunal again, the last time they pointed out that I had been there twice for the same thing within 12 months.