Quite a few of these call-outs turn out to be a two-minute fix, so it is worth trying before arranging a visit.
Start here
If it hums but will not turn, the motor is fine and something is jammed. Switch off the power at the wall, use the small hex key that came with the unit to free the flywheel underneath, then press the reset button on the bottom. If it is silent, the reset alone often does it.
Sitting idle causes its own trouble
A disposal unused for months can seize, and residue drying inside produces a smell people mistake for a drain problem. Running it briefly with cold water during a caretaker visit keeps it free.
In a villa it affects others
Where units share a drain line, a disposal pushing more solids into it than it can carry becomes a shared problem. Using it sparingly in a shared building is genuinely considerate as well as sensible.
What it does not handle
Cooking oil and fat, which set further along the pipe and combine with sand already in the line.