07 yaris bad alternator

[Yaris_guy]

So I had the wife take the 07 yaris in to the dealership today. The car's making weird noises again, sounds like the waterpump which the dealership replaced almost exactly a year ago is going bad again. Turns out it's the alternator and not the waterpump. So Toyota replaced the alternator belt once in Dec of 2010. The belt snapped off in Jan of this year. I had the car towed to the dealership to have the belt replaced for free. Now the alternator is bad and they want $600 to fix it. The wife had the car in with the same dealership a few weeks ago for an oil change and she told them to check the car and they said that everything was fine. I don't know what's going on with them but everything doesn't seem to add up. Are there any correlation with them messing up the belt and the alternator going bad. The guy there basically said that had not effect on the alternator. Any ideas on how I should go about this. We're actually going out of town for the July 4th weekend but now we don't have a car to drive. I'll probably end up replacing the alternator myself but just wanted some input. I'd rather spend $600 on some new clubs.