ESA to Universal Credit - Wrongly Advised?

Hi Gordon,
My wife was receiving ESA at nil payment (stamp only) I became redundant and our capital dropped below £16,000 in December 2018, We were advised by the DWP to claim Income Related (means tested) ESA.
The claim for IR ESA was submitted on a form provided by the DWP. After numerous phone calls - We were told in May 2019, in 2 separate telephone conversations - That my wife cannot claim IR ESA because of a change in circumstances and that she will need to claim
Universal Credit - We claimed UC in June 2019 as advised.
Uneasy we made a final call to the DWP - to be told that my wife’s claim for IR ESA had been treated incorrectly as a Contributory ESA Claim when it should have been processed as a means tested IR ESA claim!
We were advised to make a back dated claim for the IR ESA on a form which they provided along with a covering letter - We did this, awaiting results.
My wife was originally transferred from IB to ESA and received an additional element of benefit.

My wife would like to return to ESA and is prepared to make a formal complaint to the DWP, her MP and is willing to appeal if required.
Any advice on a course of action would be greatly appreciated.
Regards Willow

Hi Gordon,

Thank you for your advice - What are the first steps we need to take please?

Regards Willow

Hi Gordon

The form was an ESA 05/18

Willow