power steering pump/ replaced but was defective on 1999 Buick LeSabre

i took my car into pepboys due to the steering being hard,they diagnosed my car and said i needed a new power steering pump so they replaced it and i still had the problem,so they found out that pump was defective,after that the steering didn't work, i am wondering since the rack pinion was not diagnosed to be bad in the first place could the defective part could of caused it to go bad? thank you!

Asked by for the 1999 Buick LeSabre
Steering rack is the problem!!!
now it is but is wasn't when they first diagnosed the car,so you're saying that the defective power steering pump couldn't of caused it to go bad,shouldn't they of known in the first place,just asking,thanks!
No way I can answer that!! ... When this problem comes in the shop, I STRONGLY advise customer to replace rack AND pump!!! ... Problem solved!
thanks !!