I would email them and let them know that you've posted a blog about your experience and that there's nothing worse for a company's reputation than word of mouth. Let them know that had your experience not been so awful and had they only done what any reputable company should have done they wouldn't be losing so much future business. Of course, do all this after you make your one last purchase with your store credit.
"Life is a great big canvas, and you should throw all the paint on it you can." Danny Kaye