Power steering light on

I had power steering on my dash board light up I did not know what was wrong. I am thinking I need power steering fluid.
I go to Advanced Auto Parts store and the man there tells me he cannot put the power steering fluid in my car for me.
He said there is no way to get to it as its located in the back behind the engine and to take it to the dealership. I did and I was told I need a power steering module. That if I do not get it right away my steering wheel can lock up anytime while I am driving. I just do not know what to believe as this dealership scared me into thinking my brakes were so bad but I found out nothing was wrong with them. So I do not know what to do.