Savings and contribution based esa

Hi, firstly thanks for everything i have been awarded enhanced rates care and mobility. I also have been put support group. On my esa85 I only got 15 points for my mobility even I have other problems I have not been awarded any other points is that normal because my ftf was only 20 minutes.
My other question is. I have been getting contribution based esa but they asked if there is a change on my savings. I did not understand why do they ask
Thank you

Thanks Gordon
I also want to ask something. I am getting orivate pension of £ 75 per week and they know it. 2 years I informed them about my 90 000 insurance pay out. And 1 year later I received a letter I cannot get incıme based esa. I was already getting cb esa 3 week ago I was put esa support group again. I received award letter and onthe Esa calculation page
Extra money because you are support group
No income taken off esa
Your income related amount 38.55
However because you are entitled to contribution base esa we will pay you 111.65
My question is I cannot get ir esa because of my saving and they know it. I get private pension they know it and they say no income. I confused what should I do?
Thank you.

Thanks. I am getting correct esa but wrong explanation.

Thanks Gordon I did not know what to do. So as I told before they ask me about my 90 000 pound saving if it has changed. If it has changed they want me send new statements. So I should sent the the statements even I get cb esa. and I do not have to say any about their wrong calculation for income related esa and not putting my private pension because its their fault. I correctly informed them before and they confirmed them.