I don't know the details so I can't really assess what is going on here, but in general we wouldn't let someone be that high for that long. Surgery is usually done fairly early and if not medical therapy offered, targeted at lowering not raising the calcium.
Fun fact my endocrinologist told me to take calcium and vit d.Im really hoping the surgery helps because I might just loose my mind if it doesnt. My calcium has been like this for about three years but I was always told it was fine until recently.