The alt failure will give you a light on your dash... the battery will run the lights and accessories and still not start the car.. the op needs a new battery. I hope the shop is an honest one. You have a car towed in that needs a battery and then they know you don't know what you don't know and the bill gets big $
Any 2010s out there on the oem battery please do your self a favor and replace it before the dead of winter.
http://www.amazon.com/ACDelco-94RAGM...ype=automotive