Income related ESA - Confusing DWP Advice

My wife was on IB for decades - In May 2016 she failed her ESA assessment, went to tribunal Oct 2016 - Was awarded CB ESA WRAG, award ended Jun 2017. Continued to date as ESA nil payment (stamp only)
I finished full time work Feb18 with a settlement agreement.
In Nov18 wife was contacted by DWP requesting information on elegibilty for IR ESA ref period Jun16 to Nov18 - We phoned DWP who advised us to also make a current claim for IR ESA, they forwarded Form ESA3 05/18 - An IR ESA reassessment form.
We completed and returned both retrospective and reassessment forms. In Jan19 and Mar19 respectively our capital was below 16k and I was not working.
Phoned DWP several times and advised to await outcome.
We phoned them last Thursday and were told we were not elegible for retrospective IR ESA, and await the letter, then went on to say our current claim should not be effected by any change in circumstances - referring to me being unemployed, I was advised to complete an ESA3 05/18 Reassessment Form which I have received with a covering letter.
I phoned the DWP yesterday who advised us to claim Universal Credit - Admitting the 2 ESA 05/18 forms were sent out in error.
I am wondering should the facts that we are now claiming IR ESA as the result of a decrease in our capital and because I am not working, enough of a change in circumstances to trigger a new claim and consequently a move to U/C ?
Also is a formal complaint to the DWP an option ?
Any advice greatly appreciated
Willow

Hi Gordon

Thank you for the information.
We are Still waiting for the Form to be processed

Willow