PIP law and first-tier tribunal decisions

He was one of the first "children" , 16 in august 2015 that had had to go through the transition from DLA to PIP and the process left him traumatised as initially he was awarded nothing as if the change from child to adult meant that there was nothing wrong with him and being ill and in need of care since the day he was born counted for nothing anymore. My sons case went to first tier tribunal in may 2016 before the changes in november 2016. From receiving nothing he was awarded higher rate for care and 8 points for physical mobility. He was awarded 0 points for his ability to carry out activities safely, and his anxiety and overwhelming psychological distress even though the tribunal accepted he suffered from theses conditions (he couldn't manage to leave the car to go to the tribunal) and we had/have evidence of his continuing struggles. The tribunal said they couldn't award points for psychological distress or harm that might happen to him due to the DWPs guidance on this. When this decision was overturned we received a letter saying we didn't need to do anything as the decision would be looked at again. This decision was clearly wrong and so we have patiently waited for them to look at their decision again and change it. We have just received a letter titles Changes in PIP law and first-tier tribunal decisions, saying that "We cannot look at PIP claims where a decision was made by an appeal tribunal". Does this mean we should have reclaimed years ago despite the advice we were given?