I understand your frustration and I would be mad too, but the only way to change it, is to contact JoAnns home office.
Email them and tell them what keeps happening and how rude and useless the manager and employee was. Yes, customer service is lacking all over, because no one is bothering to take pride in their jobs and no one is informing the head offices to try to change it. I have worked in customer service at several different types of stores, WalMart, Quilt Shop, etc as well as on the phones with companies. I was taught to treat customers like you want to be treated and believe me when they don't treat me like I treat my customers, I call the head office on it. The more we put up with it, by walking away or not doing anything at all, the longer it will be this way. So contact Joanns and tell them---yes, you are only 1 person, but if each 1 person does it, that will add up to a lot of people and they will listen. Good luck and let me know what happens