I don't have a lot of experience buying fabric online. I was very satisfied with the solids I bought at fabricshack.com. The quality and color are both excellent and I got them on a good sale. JMHO. I do have a lot of friends that shop at fabric.com. This is the first I've heard of a negative experience.
I work at a corporate level for customer service in the toy industry. If you are able to talk to a manager, take it from this one that there are things you want to avoid. Try not to make it personal when talking to them. Avoid raising your voice. If you maintain a friendly but professional tone you are much more likely to get a satisfactory response. I would be careful about pointing out they may lose a customer. I was taught in training that the moment they threaten that, we shut down all communication. They don't want to shop anymore, it's on them not on us. It also helps to mention that you have purchased from them before and you have not had any problems with your order. You can also offer to ship it back to them so you can see what you are talking about. Just mentioning that you are willing to show them, instead of just talking on the phone, it will be even more likely that they will correct the issue.
P.S. Yes, I am trying to find a new job.