So, if my loan is SB, it will come off as well from my credit file even though it's not settled or not defaulted???

Hi all. It's my first time to post a thread and I am hoping that you can help me out with my problem. In January 2008, I took out a £3361 loan from Welcome finance, that included the fess and interests. And in June 2008, I lost my job and I was unable to pay the repayments. Recently, I checked my experian report and the balance now is £8500 and it is still not in default. All I can see are the red 6666666666666 from 2008. I know that when a credit agreement is defaulted or settled, it will drop off from the credit file after 6 years. But now I'm confused because my loan wasn't settled or defaulted so I'm confused when will it come off from my file. Also, last year CRA contacted me about this loan for a balance of £4500. So I'm thinking, if it has been sold to a third party, it should have been in default and welcome finance shouldn't be updating my credit file every month for another red 6 as they don't own the debt anymore. Am I right or am I wrong? I'm totally confused