DWP use of discretion in reasonableness overpayment cases

I have an appeal against an overpayment of income support next week.
Following the decsion in B v United Kingdom it appears that now the main option is to ask DWP to use it’s discretion .

I understand that following this case DWP has let Rightsnet ,CitA and CPAG have a copy of when discretion can be used in these cases .

Please can you advise where I can find the discretion list .

Also are there any other argumemts I can use .My cliant is registered blind and mentally unwell,but the above decsion seems to have thrown options and caselaw away.

Many thanks

Lynda