Even thought I'm not in your market, thanks for offering that service.
The photos in your ad do not sell your service nor have much to do with it. Scrap them and replace them with one nice photo of something film developing related. Maybe a closeup pattern of a reel or thermometer macro or something. I would not sell prints in your ad either. Move the extra info about being available for shooting to the bottom to separate it from the processing advertisement.
As far as pricing you could offer a higher price for 1 roll, and your existing price as a quantity discount for multiple rolls so photographers save your time by bringing their film in batches. I spend far more time than you developing, but I also consider time for preparation, getting tempertures right, spooling the reels, use tmax film which requires longer fixing, wash my hands real good before cutting up the negatives, and putting things away. I don't do it professionally but set aside an hour per developing session.