Completely useless

Completely not legal Please can someone help me understand how it is legal for this company to take my personal details without any judgement or any proof and place me on a blacklist for all to see and negatively influence my credit score? I had an Edgars 6-month interest-free account with Edgars after Edgers went bankrupt RCS took over the accounts and just decided without any new contract or any legal action that they will now add monthly interest to my account. RCS also just put me on Experian because I didn't pay the interest that was put on my account. How can any of this be legal?