If the fascia looks dirty, say that. If water spills from the gutter during rain, describe where it happens. You may want both attended to, but cleaning an external face is not the same as removing material from the channel above it. A clear enquiry keeps these expectations apart.
We offer gutter cleaning in Belgravia, with fascia and soffit cleaning available by agreement. Give the postcode, property sides and surfaces involved. Use safe photographs showing both the marked trim and the working area. Do not assume a request to clean the exterior includes every gutter, downpipe, window and roof surface.