Experian allows multiple adverse listings for an account that does not exist

I have had a Telkom NGN account removed from my credit listing after I informed Experian that the claim is ********** and I denied owing money to an organisation I don't know. A few months later, the same organisation listed me again. When I wrote to ask that the account be removed I was told I had to prove there was no contract, that is it a ********** listing and that I had to prove, with banking accounts dating almost 20 years back, that I did not pay the organisation. How can I prove that there is no contract and that the listing is **********? I've seen a lot of complaints on HelloPeter about Telkom NGN. Why do the credit bureaus allow them to list? Why did Experian allow the same listing to be listed again after it had been removed? To me it seems as if there are no checks and balances and that anyone can list someone, affecting their credit rating adversely, without having to proof that there was indeed an agreement.