Severely discharged battery

My GLS model (just bought 4/"18), had its first "no start" incident on 7/28/18. It had not been started at all the previous week. AA's Mobile Battery Service Computer readout said voltage on arrival was 9.61 volts, and that extensive charging was required to reach full capability. Note: No lights, etc had been left on, and the cause of this "no start" was/is unknown. The Charging System Test Results were"No Problems", with the *No Load" voltage reading 13.92V and 764.5A, and the "Loaded" reading 13.81V and 761.5A. The tester told me that the alternator and starter were fine. And even though he knew that I would be driving on a highway for the next straight hour, he told me that I needed to take it to a garage, once home, to have it fully charged overnight. I requested this service from three different garages, and all told me that that was completely unnecessary, and they do not do that anyway. The next time my car would not start was in early October, and this happened after I drove it for about ten minutes (five only city streets and five on the highway)! It was jump started, though, easily by some wonderful teenagers, and did not fail to start again until Nov. 10th. AAA came out today (10/14) and did the battery testing again. This time it was not nearly as discharged as the first time ( when turning the key did not even result in a noise). Windows, lights, radio, etc, all still worked today, and it even started to turn over, but just could not pull it off. Again, the tester said no new battery needed ( note: age is under two years). He also said the alternator was fine. This time, however the machine he was using for the tests (said it was like a voltmeter) displayed the words "loose wire", and my car would not start after he charged it, and turned it off. He said this was due to the loose wire, and he advised me to take it to a service station tight away- to have the factory alarm disengaged, the aftermarket radio replaced, and the right door latch and lock repaired- as he believed the loose wire would be found doing these things and also that one or more of them were draining my battery (note: 7/28 readout also said the "drain test" result was suspected to be 1.05A). I have no numbers for the tests done today as he never had them printed out. My car is now at a garage whose specialty is Volkswagen and electrical work. I am a bit concerned because he seems to already believe the problem is the alternator, despite that the AAA guy said, the fact that the most common symptoms are not there (no lights, no fading radio, no stalling, no strange noises or smells, add jump starting does work. The price of the Beetle alternator is crazy, (to me). And even though replacing the alternator would put me in serious debt, I know I would not have the nerve to tell him that I needed a second opinion. So, that is why I am explaining this all to you. What do you make of this whole situation? And, thank you ever so much for your help. I am incredibly grateful! Michelle