Statement not enough documentation for Experian to remove my flag, After A year still struggling

I don't know what to do anymore. I have already logged disputes about this but its not getting resolved. Homechoice handed me over to Nimble Group and Nimble Group uses SSDA to collect for them. I then got a settlement amount which I paid to SSDA and they only send me an email to say amount received and a statement showing that I don't owe anything anymore. Homechoice still reflects as arrears after more than a year of payment and SSDA Say Nible should removed my flag, Homechoice say the account is not with them anymore. Experian requires Homechoice paid up letter and dont want to accept the statement showing that I don't owe anything, and Nimble also dont send a paid up letter. How do I get this off my credit record if NO-One is willing to send me what Experian needs?