Bad Plaster Job. Help!

[Brendaneg]

We had our pool replastered last year with diamond brite. It came out bad. It was streaking, blotchy and discolored. The GC did a total of 3 acid bath treatments on it. It still wasn’t great but they offered to close the pool for us and we were tired of the back and forth. I just opened the pool and there are black streaks all down the sides of the entire pool. They did not come off with a shock and brushing. I don’t know if this is due to the acid baths, poor plaster job or something else. Does anyone have any advise??