My battery light came on in my Dodge Durango and I took it to a "mechanic" and he said I needed a new belt and new alternator. I replaced both. Two days later the battery light came on again. I went to auto zone and got a new battery and installed it. The next day the battery light came on again. What is the problem? I'm so sick of spending money and the issue is not getting fixed. What could be the problem? please help.