Charges from 20 years ago???

Hi my mum fell into financial difficulties around 20 years ago when her and my dad split up he moved out. I was still at school and she snowballed into debt trying to pay the bills she was trying to pay her way out of debt but the bank charges were crushing her she had to cash in her endowment policy and eventually some years later was forced to sell her house when the final payment was due of around £30000 due to her age she was refused a remortgage even though she was a foster carer and earning a lot of money. She wanted to remortgage to cover the final payment and buy a second smaller house to move into and rent out the bigger house which was worth £170000 at the time and the new house was £120000.
My question is can she claim any of these charges back or can she do anything about the way she was treated especially that long ago?