PIP Assessment and Money Stopped 7 Months Early

Hello All

I am just wondering if the following scenario is familiar to anybody.

My son, who is in his mid 30's was awarded PIP at a tribunal during January 2015 (He got 10 points from the tribunal judge, a big improvement on the 0 points he received from Atos about 6 months before). This was a three year award to run until March 2018 (one year was backdated). He was summoned in May 2017 to attend one of these review things with Atos Healthcare (!!). He received a letter this Saturday informing him that the PIP payment had stopped on the 4th August 2017 as he only scored 2 points (about 7 months before the tribunal judge has allowed this to be payed to).

My questions are

1) Are the DWP able to disregard the tribunal judges ruling (to be payed up to March 2018)

2) Has anybody had this happen to them. 

3) He is not going to appeal again because is was horrible for him last time round.

Is there any advice that can be given

Kind regards