Hi, is there anyone who met this problem before?

My 1999 S80 2.5TDI got problem which the power steering fluids came out due to a leak on a connected pipe. Today RAC came and found it and fixed. When we refilled the power steering fluid into, and turn on engine and try the steer, I can heard noise from the power steering pump. The guy told me to fix the pump problem as soon as posible. When I drove the car to garage, the noise disappeared. They said if I still want to changed the power steering pump, it costs 175 pounds. I am not sure if I need to do that now. And do you think garage will replace an used part into my car , but still charge as brand new? Because I can not see the part after being installed

after loosing the fluid in your PAS system then topping up with new fluid the air in the pipes has caused the PAS fluid to become airiated (air mixed with the fluid). This causes noise. After a good run the air will gradually work its way out and the steering will be less noisy, sounds like this is what your problem was. If the leak is fixed and the noise gone then I see no reason to replace your PAS pump.

Thanks paul. The car now seems to be what you said. I will keep my eyes on it. See what is going on.