2003 Volkswagen Passat CV joints or whole axle?

Hello
I had my car in the shop for a routine oil change and the mechanic said my cv boots were leaking and needed repair, at the time there were no signs or symptoms of this so I declined to a tune of $550. Now two weeks later when I turn left or right the car knocks. Is this a result of that diagnosis? When I called another mechanic to compare repair prices he told me the whole axle needed to be replaced on both sides without even looking at it. He said if I only replaced the boots/joints that the shaft would eventually get ruined. Is this true? Can I only replace the joints? Thanks for your time.
Jennifer