1992 Nissan Sentra Confirm that their is an Electrical Issu

Hi, I have a '92 Centra. Just after the new year a 1 month old battery died, we had the alternator tested and it passed 3 times, the shop we purchased it from said it didn't have enough cold weather Ampage; we replaced the battery and just over a month later the car died again. Same exact symptoms, the dash would start to make a clicking sound, the battery light and emergency brake light go on and eventually the car dies out. After a few hours it will start again but once you put on the radio, rear def. Etc. The car dies out (we where able to back it up for the tow truck and it died out) The store said at 1st it was they put a new battery in and it still wouldn't start it is the alternator, then retracted and said the alternator is producing more ampage. Trying to get an idea of what could be wrong with the electrical system or if I should take the alternator somewhere else to be checked. Thanks