Overpayment trouble DWP ignoring the issue for 2 months

We finally managed to sort out the ESA/UC crossover for my relative with a delay in receiving UC at first only half was paid, they left off the LCWRA component. Work coach fixed the issue, but there was an overlap in his payment of ESA. He was told it would be taken back in installments. Arranged with work coach £10. Not only have they taken the ENTIRE amount back, throwing his finances into chaos as it wasn't what was planned for, but they took almost SIX TIMES the instalment agreement, leaving my relative with half his amount of cash to live on for two months now! He is now at the bottom of an overdraft and credit card, with no extra cash just us to survive, whilst the dwp refuse to pay him back!The debt team say they cannot pay it back as ESA never repaid them. The UC team say it's ESA and they can't pay him back and the ESA payment centre has the most ignorant woman ever who appears not to comprehend English very well, refusing to allow it to be referred to a manager. Meantime 13 messages in nearly a month have been left for the work coach who has not bothered answering AT ALL! I am told this qualifies as hardship, and they should waive this debt as it's not his fault, but they are now completely ignoring all work journal messages and calls are useless, they all pass the buck and nobody will pass it to a manager, this is theft now too, as it's eating into his money, they've already taken the ENTIRE overpayment back ! Who can we turn to? It's blatantly obvious only £400 of £809 was paid out to him in April!?