My warranty reads virtually word for word the way your builders does.
It means that the leak is not covered. However, it doesn't mean that I'll hose the buyer on the repair.
On pools over a year old I ask the homeowner to pay the leak detection company and I'll come determine the labor intensiveness of the repair.
On one like yours I'd just send a mason and a helper on a weekend and have the homeowner pay them their overtime wages in cash with a 4 hour minimum.
This excites my hands because they know that this should be no more than an hour repair.

waste is correct, this is a repair that could most likely be handled by a homeowner very affordably. On a repair like this I'll usually lift the leaking rock if it's loose, chip the old thinset off, cement it back in, and grout.
If the rock isn't loose I'll take and chip out the grout and then regrout.

I'm sorry if you feel that your pool should be covered under warranty because it shouldn't. This is not the structure, it's one of the items external to the structure.
If your car needed brakes after three years does that mean it should be covered under warranty too? No, it's an item thats excluded.

I'm equally sorry that your builder trying to hose you on the repair, the most it should cost him is 50 to 200 to have the repair addressed.

See ya,
Kelly