SWG causes rebar stain

[Crystal Clear Pools]

I have an Anthony and Sylvan pool (36000 gallons) built in 1999 it is plastered with ansel brite. I installed a Goldline SWG about 3 years ago. The unit works fine. My problem is that im getting stains from the rebar in the concrete. The ansel brite plaster bubbles then cracks off and you can see the bare gunnite and the metal stain seeping thru. The first stain was at my swim out area. They sent a tech out and he drained about 12000 gallons from the pool and cut into the stain and removed the rebar and patched it. Several weeks later the stain returned. Again they cut in removed more rebar and patched it. The next year the Stain returned (sounds like a bad nightmare doesnt it)they drained cut and patched it and it finally worked. But I have a big ugly patch. Now this year I have a big stain at the very bottom of my pool. Its the same thing, rebar. It bubbled up and the plaster broke off. You can see the bare gunite and the stain seeping thru. Now Anthony and Sylvan pools say they are going to drain, cut and patch this rebar stain to. Remember its 36000 gallons. And remember that every time they have to drain, I have to fill , condition, add salt and chemicals. Around 500 bucks every time. The tech said there having alot of these stains due to SWG. He said if the rebar is to close to the surface you'll get a stain and now that they sell SWG at Anthony and Sylvan there much more careful when building the pools. Wish they had that kind of Quality control when I was having my pool built in 1999. I've talked to several people and I realize that Rebar stains are not uncommon. My problem is the stain this time is dead center in my pool. And I dont want a big ugly patch. Id love for them to patch it and replaster the pool but I dont believe they will go for that as my plaster is only guaranteed for 3 years. Any thoughts or suggestions would be appreciated. Thanks Steve

ph is 7.5, cya 80, hardness 250, al 100-120, pretty normal.