Hi, my name is Pash68!

Hi everyone, have joined up as am hoping for a bit of advice or even just some help understanding ESA / PIP assessments. I have been on ESA higher rate for 2 years and I applied for PIP in Oct 2016. Was sent for an assessment which I failed. I appealed and in April was awarded higher rate daily living by the Tribunal for 10 years. I have a lifelong disability which the tribunal recognised cannot 'get better' and which they stated on the Decision Notice makes my day to day life 'severely limited'. Yesterday I received a letter from the Health Assessment Advisory Service calling me to an assessment for my ESA. I do not understand why I should be assessed for ESA if a tribunal has recognised the effects of my disability on my ability to manage my daily living and has given me a 10 year award....surely they can hardly fail me at the ESA assessment if a PIP tribunal has already acknowledged my disability and the effect it has on my life? Can anyone explain this as I am finding it quite confusing.