HELP WITH WAIVER

GOOD MORNING,
After many months of fighting the DWP over, overpayments, I have got the final dissection from (ICE)
Independent Case Examiner and it seems they were putting the blame on CA and have also said that Several times that I have pointed out to them several times their wrongdoing each and every month.
So now after all this time, all I have is a £2500 plus bill to pay, This is after the £989 over payments we have already paid in the last few months.
But I'm seriously thinking of asking for a waiver from the lady at ICE told me it should be okay to do, I was wondering if anybody here has ever done this before and how long it has taken to do.

Also people how long has it taken if it was stressful for you

Thanks for your help