If you change the way you charge your customers, please try not to frighten them.
If you are charging them once every other month, don’t let their bills convince them that you’ve charged them twice as the previous months!
Shouldn’t have been possible to send a clearer bill? Maybe something like this…
Something that communicated the change in the billing system without adding noise.
Something that informed customers instead of made them worry.
Something that made their customer a bit happier.