COLP ESA IC or CB

Hi. I was medically retiired in 2010 after suffering a stroke. Initially I received contribution based ESA. After a year the payments reduced and I was told I'd been put on Income Related ESA. It was explained to me that I could have CB for 12months as it was based on my previous years NI contributions. As i had stopped working this was no longer appropriate and i started getting IC. As Income related i was told that my small works pension would also be counted as income before my payment amount was decided. And sure enough for the past 11yrs in every letter I've received my monthly pension been deducted from my monthly payment. When all the different COL payments were explained and listed i was really pleased to see ESA income related was one of the benefits listed. so when no payment arrived i was puzzled. I followed procedures and after various emails, letters etc found myself on phone to ESA as GOV.uk advised i didn't get payment as i didn't get ESA. I spoke to an advisor and explained my confusion and frustration. I was put on hold and when he returned he told me I'd been switched back onto contribution based ESA as they'd worked out it paid a slightly higher amount. He said that every year when they work out payments they calculate both and put claimant on whichever pays greater amount. I was aghast as I confirmed with him that for an extra £1 in my payment I was losing out on £650 ! In addition i've never known them to ever put claimiants needs first in this way. I'd never been notified of any change, and as far as I knew IR was the only ESA my circumstances were appropriate for. I'd never even known there was a choice. Then I asked , why then if i was now on a benefit that wasn't means tested why is my pension still being deducted? It feels as if they keep moving the goal posts so i'm never on the right side and can never ever get anything extra. I confess his explanation went over my head a bit. something about using the contributions from my pension? i have slight cognitive issues after a stroke and can only retain so much information. Has anyone else encountered this problem ? Can anyone explain it to me please ?