Should I have been awarded f(ii) as my descriptor for 'getting around' for pip

Hello
Can anyone advise

I have been awarded pip for mobility at the enhanced rate and given descriptor 'e'
"can walk 1 to 20 metres but no more"

I believe I should have been awarded f(ii) on the following basis

I have a fnd condition which has impacted on my ability to walk, the following facts are as follows

Although i can walk upto 340 metres (then i have to continue in a powered wheelchair) I am unable to walk ANY of this distance within a reasonable time, nor repeatedly, whereas being given descriptor 'e' is stating i can walk the first 20 metres as defined, this not the case

As part of my pip claim evidence was provided by my doctor stating 'takes 5 minutes to walk 15 metres'
Although I have made it clear in my pip application that I can walk 340 metres at 30 metres per minute (still 'not within a reasonable time')

I am aware, of-course aware if i was awarded f(ii) this would have resulted in the same number of 'points' but I can assure you this is not about points, its is about getting a accurate reflection of my ability to mobilse and I believe f(ii) is more indicative of my ability than 'e'

thanks