Yikes 1995 Dodge Neon in Distress

Help please! My car broke down and a reputable garage told me I needed a new alternator and battery. I couldnt afford to have the work done there so I had the battery charged(the auto parts store I bought it at stated that it was still a good battery), bought a used alternator had it tested, and paid someone to change it. Two hours later my car died again with no power and I was unable to get a jump as the battery wouldnt hold a charge. I took the battery to the auto parts store and asked that they warranty the battery and give me a new one. About 2 hours after putting in the brand new battery and driving home, my car died yet again. Can someone please tell me if somethng else is draining the power from my battery and what should I do now? Im tired of being ripped off by garages and Im at wits end with this car. :Cry: