main.php

<?
function process() {
  $groups = $this->Group_model->getReadyToPublish();

  foreach ($groups as $group) {
    switch ($group->type) {
      case 'vk':
        $result = $this->Pub->vk();    
      break;
      case 'ok':
        $result = $this->Pub->ok();    
      break;
      case 'tw':
        $result = $this->Pub->tw();    
      break;
      case 'fb':
        $result = $this->Pub->vk();    
      break;
    }

    switch ($result->error){
      case 1:
        // process error
      break;
      case 2:
        //process error
      break;
      ...
      case 0:
      // charge user and move to next group
      break;
    }
  }
}
?>

Line 17 needs fb()