where is the power steering fill reservior on my 2007 pontiac g6?

Power steering is electric so there is no power steering fluid. The mechanic I went to said it was an electrical problem that I would need to have the dealership fix because he didn't deal with electronics. I didn’t have time to look into it because I needed it fixed. So, the dealer told me a sensor needed replaced in the steering column....so after almost $1000 in repair cost I find out that if I would have just bought A replacement steering column (which would have replaced the sensor inside it) I could have saved a ton of $$$$....‍♀️