do you know how much the guys who put these up charge?
how much does it cost just to put them up in the first place,
how many people can actually do this job, and actually put it back to the way it looked when it was brand new? not many, but you can, your the expert
by the sounds of it, its a one off, if not and its part of a regular window cleaning round then the roof will be less,
but he is going to have to clean it and get rid of all the little bits that stay around, cleaning the gutters to perfection especially at that height isnt a quick whip or flash with a brush, and also the dirt underneath the sill can take a while to get out
insides are back breaking, all the merky water drops on you and you get hot sweaty etc etc etc, for £350 it will look brand new, not just what they could do with a sponge and a hose