Today's calendar is always provisional
An emergency displaces planned work. Rescheduling has to be quick and the displaced customer has to be told.

Plumbing
Plumbing runs two businesses at once: booked work you planned for, and urgent work that arrives at nine in the morning and has to go somewhere today.

What the work actually involves
An emergency displaces planned work. Rescheduling has to be quick and the displaced customer has to be told.
Much of the work cannot be quoted until it is opened up. The customer needs to understand that before you arrive.
Knowing what is installed before you leave the yard is the difference between finishing and returning.
In ManePilot

Questions
Yes. The schedule is built to be re-planned, with day, week and month views and status on every visit.
Estimates can be created against a job and sent for approval, so work carries on from something the customer agreed to.
Related
Set up your services once, and the schedule, booking page and invoices all work from them.