Modifying appointments+

Hi,
I've decided to take the plunge and modify this plugin for many reasons. First things first, I want to add hours for each service - without using the 'add new user' method. I have added a new tab called 'event hours' and I have loaded in the services as my events. I have added a new table in the database with the same structure as the worker_hours table.
My problem is this; When I click on the event to add hours to, the event list (services list) resets to 'no specific provider'. How can I write to my table in the database?
Here is the code I have for when the tab is loaded,

<?php

case 'event_hours': _e( '<i>Here you can define the hours for your events.</i>', 'appointments'); ?>

<?php
$events = $wpdb->get_results( "SELECT * FROM " . $this->services_table . " " );

?>
<?php _e('List for:', 'appointments')?>
 
<select id="app_service_id" name="app_service_id">
<option value="0"><?php _e('No specific provider', 'appointments')?></option>
<?php
if ( $events ) {
foreach ( $events as $event ) {
if ( $this->event == $event->ID )
$s = " selected='selected'";
else
$s = '';
echo '<option value="'.$event->ID.'"'.$s.'>' . $this->get_event_name( $event->ID, false ) . '</option>';
}
}
?>
</select>

<script type="text/javascript">
jQuery(document).ready(function($){
$('#app_service_id').change(function(){
var app_service_id = $('#app_service_id option:selected').val();
window.location.href = "<?php echo admin_url('admin.php?page=app_settings&tab=event_hours')?>" + "&app_service_id=" + app_service_id;
});
});
</script>
<form method="post" action="" >
<table class="widefat fixed">
<tr>
<th style="width:40%"><?php _e( 'Event Hours', 'appointments' ) ?></th>
<th style="width:40%"><?php _e( 'Break Hours', 'appointments' ) ?></th>
<tr>
<td>
<?php echo $this->event_hour_form( 'open' ); ?>
</td>
<td>
<?php echo $this->event_hour_form( 'closed' ); ?>
</td>
</tr>
</table>

<input type="hidden" name="event" value="0" />
<input type="hidden" name="location" value="0" />
<input type="hidden" name="action_app" value="save_event_hours" />
<?php wp_nonce_field( 'update_app_settings', 'app_nonce' ); ?>
<p class="submit">
<input type="submit" class="button-primary" value="<?php _e('Save Event Hours', 'appointments') ?>" />
</p>

</form>
<?php break; ?>

Can you help? Thanks.