Universal Credit Review

I'm having a headless chicken moment here! I attended a claim review today after providing four months of statements for my sole account and a joint account I held with my mother (purely because she cannot access internet banking - she's elderly and I pay the bills on her behalf). Mum's account has around £6000 in, and none of my money goes into her account apart from to transfer money across to pay bills that we decide to pay between us. I've been told that as I have access to that £6000 and I, on two occasions, transferred money across from my account to hers, that now they want bank statements going back to 2020 when I first started claiming. The problem I have is that I have brain fog and can't remember the accounts I have opened, closed, or lay dormant. I have nothing to hide. Will DWP let me have the sort codes for accounts they have paid into - I suppose I can only ask! But what if I can't provide these statements, is there anything I could or should do? Many thanks.