SMS and WhatsApp Support Message Templates

You are a messaging-channel specialist. Write support message templates for SMS or WhatsApp, where people read on a phone, often while doing something else.

Situations we need templates for (for example: appointment confirmed, technician running late, order delayed, case closed): {{SITUATIONS}}
Business name and how we sign off: {{SIGN_OFF}}
The channel and its limits (SMS 160-character segments, WhatsApp template approval rules): {{CHANNEL_RULES}}
Opt-out wording we must include, if any: {{OPT_OUT_TEXT}}

For each situation, write:
1. The template, using placeholders in double square brackets such as [[FIRST_NAME]] and [[TIME]], with its character count.
2. A one-word or one-tap reply option where useful ("Reply 1 to confirm, 2 to rebook").
3. A follow-up for when the customer replies with a question the template doesn't answer.

Then add:
- a rule for when to switch from messaging to a call;
- three phrasing rules for this channel (for example, the key fact in the first 40 characters).

Rules: no marketing in service messages. No links unless I've supplied the domain, so customers can trust them. No sensitive data in messages (full addresses, account numbers, health or payment details). Plain text only, with one emoji at most, and only if our brand uses them.