UC Migration & CB ESA

I called ESA yesterday as I had a letter to say my claim was closed as I had claimed UC - managed migration and the date ESA Claim closed is the date I did the switch to UC.

I was calling to see when my final payment of ESA would be, to see whether I needed to apply for an advance payment of UC.

The ESA employee told me that my CB ESA would still continue to be paid at £145 per week every two weeks.

I was not aware I was on CB ESA, and thought this had expired a long time ago.

I was originally on Incapacity Benefit having finished work at 30 due to ill health, I switched to ESA in 2013, why am I still getting CB ESA, and why are ESA Uprating Letters failing to breakdown what my ESA is made up of?