My lawn company has found leaf fungus on the plants in our front yard. We are a new house, going on one year, and we have one small tree in the front yard and six small bushes. All are infected. They want to treat the plants "to help them get established." They want to charge $250, but after we've told them no (and apparently a couple neighbors have done so as well), they have since said they realize that with so few plants, we could replace them for the same price, so they are going to come back with a better offer.

My question is two fold: (1) Is leaf fungus worth treating? Will it kill the plants if left alone? Or is it just unsightly? (2) What sounds like a reasonable price for treatment?

Photo below of what they gave me as samples from our bushes (to clarify, I am in SC zone 7b/8a). I also added some photos of my own. I do see the spots, but the plants look relatively healthy to me. Don't know if this is something that needs taken care of not. I have no experience in this area.

EDIT: I have added a clearer photo of the leaves they gave me without the plastic bag that some comments refer to.