Woolworths poor service

I had an account with woolworths and they handed it over to 3rd party, account has been paid in 2018 february. But the account still reflect badly on my credit. I have engaged with the 3rd party Nimble.they told me only woolworths can clear the account off credit beuaru. I have been emailing woolwoths the paid off letter but they not assisting me. This affecting my credit and its been a year now since account paid off. Im unable to move forward in life because of this account.