I have two rebar stains right next to each other near the top of the pool.
The pool is around 20 yrs old.

I was told this would have to be repaired by either cutting into that section and doing the repair or re-plastering the whole pool. Which would be the best route to take? I'm just worried if I just repair these then others may appear.

I did a search for this problem but it seemed like it was just to get rid of the stain.