Monthly repetitions not respected on Action Schedule

I found someone who should have got monthly reminders was getting them every reminder run. Looking at the code it seems there is no handling for monthly reminders & it is treated as hourly

// if repeat is turned ON:
if ($actionSchedule->is_repeat) {
$repeatEvent = ($actionSchedule->end_action == 'before' ? 'DATE_SUB' : 'DATE_ADD') . "({$dateField}, INTERVAL {$actionSchedule->end_frequency_interval} {$actionSchedule->end_frequency_unit})";

if ($actionSchedule->repetition_frequency_unit == 'day')

{ $hrs = 24 * $actionSchedule->repetition_frequency_interval; }

elseif ($actionSchedule->repetition_frequency_unit == 'week')

{ $hrs = 24 * $actionSchedule->repetition_frequency_interval * 7; }

else

{ $hrs = $actionSchedule->repetition_frequency_interval; }