MB service

Three years ago in 2011 I had that famous sqeaking noise coming from underneath the hood when turning the steering wheel on my 98' MB ML320. Bennette's Motor World said it needed a new steering servo pump and reservoir. Roughly $600 for the pump, $400 for work. Oh well, if the cars needs it, what can you do. Probably cheaper than at the dealership. It took them several days to order the parts and to repair the car and I paid around $1000. Three years later, same symptoms, so I went again and they diagnosed again new steering servo pump and reservoir - a known common problem for the ML320 they say. This time they felt sorry for me and because I complained, they offered the pump for only $400 plus work...around $834 to repair. I was not too happy about this, so I googled...... steering servo pump is around $100-150 from a parts shop in Atlanta.....and the common problem in 95% of the cases is the O-ring of the reservoir, not the pump. So I went back, but they insisted it is the servo pump and it will cost $834 to repair. I went to Express Oil around the corner, and a VERY KNOWLEGEABLE guy, told me it is leaking from the reservoir! He installed a new o-ring (a $2.50 part, and the new reservoir just in case, $20) for $148 including tax!!!!! It is working like a chime again, the noise is gone. I am speechless...and I am wondering if that new power steering servo pump three years ago was necessary in the first place. I am also wondering about the expertise of Bennette's Motor World, and about the reason why they are not accredited with the BBB. I feel as if I was robbed blind over the last few years! Feel free to make your own judgement!