public function validateService(SLN_Wrapper_Service $service)
 {
     if ($service->isNotAvailableOnDate($this->date)) {
         return array(__('This service is unavailable ', 'sln') . $service->getNotAvailableString());
     }
     $ids = $this->getDayBookings()->countServicesByHour();
     if ($service->getUnitPerHour() > 0 && isset($ids[$service->getId()]) && $ids[$service->getId()] >= $service->getUnitPerHour()) {
         return array(__('The service for this hour is currently full', 'sln') . $service->getNotAvailableString());
     }
 }