My battery is putting out too much voltage..do I need a new aternator? on 2005 Saturn Vue

I was told by 2 people at different auto zone stores. Battery indicator light comes on.

3 answers
Possibly. Are they willing to guarantee their 'diagnosis'?Depending on the cost of the alternator VS. the cost of diagnosis is it worth the gamble?
if it is overcharging then the reglator inside the alt is probably shot you will need a new alt
battery when votemeter checked shoul be 12-12 1/2 volts , shoul reed 13 if alternator is working when engine is running