Blacklisted for an account paid up a year ago!

I am utterly disgusted with the services from Woolworths management. They have people in customer services who has no powers to resolve matters. I paid up my credit card on the 18th November 2018 and found out a year later that i have been black listed. How is that possible when i even have the paid up letter. Woolworths never updated my profile and in the meantime i have a bad credit name because of someone who did not do their job. It has been disappointing 7 days and no action from management. This is the first step. Tomorrow i will be on twitter. We did not forget how this very company has dressed up our kids like ******s!