What do you send when you are the one cancelling?

If you have to cancel, your message decides whether the customer understands or gives up on you. Four elements belong in it.

Immediately

The longer you wait, the greater the chance they are already on their way. Send as soon as you know, even without a solution.

Say it plainly

Not "there is a change in the schedule" but "your appointment tomorrow at 14:00 is not going ahead". Vagueness produces phone calls.

Offer an alternative straight away

A concrete new time, not "we will be in touch". Anyone who can rebook immediately stays a customer; anyone who has to wait looks elsewhere.

Make replying easy

One reply to confirm. A customer who has to phone during your busiest hours is a customer who gives up.

For a larger cancellation

Send individually, not as a group message with everybody visible. And have somebody ready to handle the replies — they all arrive at once.