Paragon Finance

Looking for advice? I initially took out a loan with Universal credit for £10K over 10 years the start of this loan was back in late 1994. Total sum to paid back amounted to £15K. Made my fist payment of £241.63 and continued for the next 41 months. I then got into some financial difficulties due to a failed business and missed 3 monthly payments. However then commenced payments again for 10 months then had other finance issues and missed 3 months again. Then commenced again for a further 18 months this took me up to June 2001. However because of the missed payment Paragon took me to court and I got a CCJ. Total amount paid during these periods was £14,931.83. During the period of this loan the original lender Universal Credit went bust and the loan was passed to Paragon Finance. Then subsequently the loan was then sold to Robinson Way. It was during the Paragon and Robinson Way when they started to administer various charges totalling £1328.13 and additional interest of £9,791.19. I also found that PPI had been added to the loan without my knowledge totalling £3,782.40.
To date I have paid them £20,181.83 and would be interested in advice on how I can make a complaint to these companies who seem to have gone bust or morphed into another business?