Enhanced PIP mobility component

I contacted DWP regarding an article I had read saying that if I had been refused the enhanced rate because I was in receipt of state pension age I could apply under section 27 as long as I met the criteria. There were eight criteria and I met seven of them. Criteria eight was that a claimant had not informed the DWP of a change in circumstances since the initial award. I had a stroke in. October 2017 ( after my initial assessment and award)and retired March2018. According to the DWP in order to qualify for the enhanced rate when I applied for re assessment in 2019 I should have not mentioned the stroke. My form should have been identical to the first one! Here is an extract from the letter “The law says we cannot award or increase the mobility part of PIP for claimants state pension age or over. Whilst I accept your mobility has worsened, I cannot look at your award as this happened after you reached State Pension age. Therefore you will still receive the standard rate of PIP to help with your mobility needs.”