FIRST CUSTOMER NIGHTMARE-BEWARE OF FRAUD

Recently had a bad experience. I was hired as a seamstress for a company, Balls Out Rugby, owned by Regina Jones in Marietta, GA that I would design some T-shirts, hooded sweatshirts, and bags. I would be paid a flat rate for the designed pieces and applique work. I completed the collection. I gave my invoice for the work to be paid, and keep getting emails from the lady(who refuses to take my calls)that it wasn't to her specifications and is withholding payment for the work I did. I made the clothes according to specifications, (I gave her the notes taken from initial contact and distribution of materials), sent pictures along the way of the progress, so she could see how it looked. I went literally back and forth with her, and told her that regardless she has to pay me for the work I performed. If it was not the way she liked it, I could have fixed it for her, after the payment. This is so horrible. I worked really hard on all the wear, and she was MY FIRST CUSTOMER. I am thinking about getting a lawyer and suing her for payment. We did not have a paper contract, it was oral, but there was witnesses. I asked for a paper contract, and she said no we are ok, you trust me right? I was stuped and I don't want that to happen to anyone else. That lady is a fraud, and I will get everything in writing from now on. Any advice on who I can report her to for bad business practices? Or how else I can get my payment?