As you are 68 you cannot be receiving ESA, so I assume you are talking about DLA or AA? I know that DLA have a 'Right Payment Program' where they randomly select people to review, so that might be what has happened in your case.
The Right Payment Programme If I have assumed wrongly, or you have any further questions, please come back and ask them on this topic/thread. You will be able to find it easily in future if you make it a favourite' now, or bookmark it