So basically the OP, an Independent Contractor, in some way annoyed the customer, Dan, Goodwin's representative. So the customer does not want to do business with her any more. Their choice. As a independent contractor, the OP has the right to do business with any company she wishes and to stop working with a company for any reason - or for NO reason. The customer has a right to decide not to do business with any independent contractor for any reason - or for NO reason. Is it "fair" to the OP that she's done outstanding work but the customer refuses to work with her any more? If a customer doesn't want to do business with an individual or a business, it's their choice. Would it be "fair" to Dan and Goodwin to work with her when he doesn't want to? With an outstanding shopping history, the OP will probably land on her feet and my advice is for her to accept that the customer doesn't want her and move on to other companies that do want to work with her. There are lots of companies.
And, yes, I did not shop with Goodwin years ago because they had late payment issues, well documented on this forum and on Volition. They straightened that out several years ago and they now pay like clockwork. Good company. Low pay on the shops I see, but they have a few clients I like.