Was my friend overcharged for mulching?

My 91 year old friend who owns a house in the Palisades area in Washington DC was charged by a gardener $1200 for mulching his front and backyard. His property is fairly sized I guess since it’s just one of the many houses in this rather well-off area. But does anyone have an idea if this charge was the more or less going on rate these days or is it too much?

We plan to call the gardener asap but is interested in getting some helpful info if possible. Thanks!