They came the next day after I phoned them, within the indicated time range, and quite quickly identified the problem (an igniter that had too low amperage so needed to be replaced) and did the repair.

They also gave us good advice (for a gas stove) about ALWAYS running the fan when we use either the burners or the oven, both to avoid overheating and possibly burning out the circuit board, and to avoid carbon monoxide buildup.