DWP wrong!

My daughter has just been to the tribunal for my grandsons claim for PIP and the DWP representative opened by conceding they had made a mistake. He has been given standard rate of daily living and enhanced mobility!
What really annoys me though is this has taken 1 year 3 months since his assessment to sort out which means they have missed out on PIP, Carers allowance and diabled child credits. Yes I know it will (hopefully) be backdated but she has struggled for all this time.
The DWP dont seemed to realise either the mental strain waiting like this puts on families.
We knew we were right but its great to have that acknowledged!