ESA and inherited (survivor?) pension?

My mother is in receipt of ESA and a few months ago was told that she would need to repay a debt of over £8,000 due to my father/her husbands occupational pensions.  These total around £130 a month and then a Miners pension that varies from £60-90 every 3 months.

She received letters that advised her that they were to be disregarded in 2013 and from what I can see on the internet they should still be disregarded unless there is a recent change of rules. Rules are V1127 and V1128 are mentioned by other people.

She contacted them to be told that this was not the case and there would be not change to her benefits.  

I contacted them myself a couple of weeks ago and after much discussion was told that their decision was correct and that she could not reduce her payments as they only totaled around £20 or so being deducted as they were taking all of her late husbands pensions into account.

Is there any definite clarification to this V1127 and whether it should be disregarded or not?

She has gone from upwards of £250 per fortnight to roughly £120-130 and she is struggling with money due to the large reduction.

Thanks for any help you can provide