when he gets it back, should he have extended warranty or if the same problem resurfaces, does this mean his money is lost?
Pretty sure there are no laws that dictate that so it is up to the agreement made
before repairs are made, AND what was found to be wrong the second time.
If the computer came into my shop for the
exact same "repair", then the clock would reset for that
specific repair, and a new warranty repair period would start. But that's just me because I will take a loss to keep my customers happy, and returning, and spreading good words about me.
But again, it depends on what was broken and what was fixed the first time. You say the problem was "
a graphics issue on an imac which was causing the imac to freeze". But from a technical standpoint, that could be the cart pulling the horse.
That is, it could have been a power problem causing the graphics to freeze making it appear the imac was locked. It could be corrupt drivers, malware, or all sorts of hardware failures. That is, many different problems can present with the exact same symptoms.
If something else broke this second time causing the same symptoms, that's a different repair.
This is where getting a good, honest repair shop matters.