G'day all
The main thing must be homework.
You must avoid agency work - where folks say they can do
the job, but actually act as agents.
I note that Gadge's link is a good one, but you wold need to
confirm the 'service' is done in their workshops.
Both reel and bottom blade need sharpening.
Avoid someone who fits a pre-ground blade and says that's enough.
Pre-ground blades still require a grind after fitment to the sole plate.
Here's an info sheet ...