Helen,
Written communication is sometimes a 'bugger' to get right.
Maybe before you post stuff though people's door, ask a friend to read your material and ask them to be honest with their opinion.
I'm also not sure I agree with writing the cost of the clean on a 'canvassing' leaflet you post through people's doors. That's more guess-work, (I guess) since I doubt you check the rear of every house you put them through.
I also think potential customers are more concerned about how you look (do you look like you're going to 'rob them'?), rather than just a price.
Just my thoughts!
PS.
It's 'Doh!', not 'Dooh!'; 'Doh!'