I always think you are on dodgy ground if you advertise one price and then quote another - even if it is a minimum cleaning charge.
I saw a leaflet recently from another carpet cleaner that was headed in huge bold lettering "FREE Carpet Cleaning" with no gimmicks, no hidden costs, honesty blah blah blah.
The deal was basically that if you had a couple of rooms cleaned you got another one for free. Already not exactly living up to the "FREE carpet cleaning" billing it was given.
Not so bad, but right at the end in the small print after all the promises on the leaflet it stated a minimum cleaning charge of £65. No hidden costs or gimmicks my ar*e!
That is the kind of thing that really winds me up.