2000 VW Jetta alternator

Hi, I have a 2000 automatic VW Jetta with 55,000 miles. I bought it used from a dealer in 2003. A month ago my battery light went on so I got a new battery. A few days later the battery light went on, my radio shut down, and the ABS and emergency brake lights went on. Everything then shut down and my car died. I had it towed to my mechanic and he ordered a new alternator. I picked it up and the next day the same things started to happen so I parked it up before it shut down. I took it back to the mechanic and it just so happens that the new alternator was bad so a new one was sent and installed. I picked it up again and this time it took about 3 days for the same thing to happen again. The battery, ABS, and brake light went on and was flashing and the speedometer, gas indicator, and everything else on the panel went down to 0. There is no dealership or mechanic specializing in these cars in the U.S. Virgin Islands. I called the dealership in Florida that I bought it from and the only suggestion they could give me was to get a VW brand alternator (I'm not sure what kind the mechanic put in). Any information or suggestions would be greatly appreciated. Also, the last time I picked it up from the mechanic, the airbag light was on. I'm sure this was b/c he was working on it, but how do I get it to turn off? Thanks!