Subaru Legacy Steering Help!

I brought my Legacy to a mechanic last week with a few problems, including the steering squeaking. Turns out the hose was dried out and leaking in 3 places and I needed a new pump. I got a call on Friday saying they replaced both but now with the new parts, the power steering is not working when idle or slow, only when the speed picks up. They then replaced the (new) pump and hose and put in a new rack, but to no avail. The same problem was happening. They tried it again with a 3rd pump and hose and 2nd rack and it STILL wasn't working. They've called Subaru and other mechanics and everyone says that what they tried should have worked.
Has anyone heard of something like this happening and have a solution? If not, does anyone have an idea of what else they can try? They've had the car for a week now and we wouldn't mind getting this fixed so we can get our car back.