ESA and group income protection

Team
Looking for advice please, January 2018 I was finished work due to ill health, my employer at the time paid into a scheme ( I made no payments) where I get 50% of my salary until I reach retirement age and also meeting the criteria of the insurance company. So I was unemployed, paid tax on the monthly payment but paid no NI contributions.
Contacted DWP by phone as I explained I did not want a shortfall in my NI contributions and was informed that I was entitled to ESA, filled in the forms and stated again I was in receipt of group income protection, was then invited to a face to face at my local job centre ( to see how they can help me) they talked about how they could help me back into work, if I could work I would still be in the job I loved, and for the 3rd time told them I had GIP, and was told yet again I was entitled to ESA.
ESA contribution based payments started along with my GIP and eventually was placed in the support group, since January 2018 I had received 3 letters stating I am entitled to continue to receive ESA.
Now I receive a letter from the fraud and error department asking if I made and payments to the GIP and are checking if I am receiving the correct benefits.
Phoned them up explained all this to them, they could see on the system where I had declared my GIP, and they would pass this on to the fraud team and they would call me back.
Fraud team called next day, so I explained it all again, again the could see where I had declared my GIP, asked me to put it all in writing and state whether I paid any contributions to it, so all this went into a letter and I told them that I have declared my GIP over the phone initially, by mail and also face to face, that I had also received 3 letters from them stating I was entitled to ESA, and that I was concerned as to why this letter had been generated and would like an explanation, I was then told it would be going to a decision maker (keyboard warrior) as to what happens next.
At no point have I tried to hide my GIP but it seems I am guilty over something until proven innocent.
I would be grateful for your thoughts on the above, I have discussed this with my local CAB and their view is I am the innocent party due to a cock up at the DWP, I would be interested on your views as my opinion is, I make a mistake, I pay, you make a mistake you pay.
Sorry for the long tale of woe

Scratchgolfer

Gordon
As my claim was only last year I presume it is new style ESA, I informed them 3 times, on the form, by phone and face to face, I don’t see I could have done much more.
As I said they can see it was logged on the system.
So even though through their incompetence I could still have to pay back any monies paid to me,
SG