Reviews for Mophie Juice Pack Plus Battery Case for iPhone 4S/4

I have had two of these now and I have had a little problem with battery either not charging or becoming very loose. The first one I would have to jam it into the phone with my thumb to get it to charge. Customer service at Mophie was great and they replaced it. The second one kept falling off and eventually I lost it so now I am stuck with the case minus the battery. I can't find a way to buy just the battery. If I could afford another I would buy it again, but . . . still thinking there must be something better.