Do both. Point out the problem to them and see if they make an effort to remedy the situation. If it becomes blatantly obvious that they don't give a rip and don't intend to do anything about it, DO report them, certainly in writing, with details. If there were extenuating circumstances of which you were not aware, the attendant can try to explain that to management. But management needs to know that a paying passenger requested service and was not served, and was dissatisfied, with the details. And if service was not rendered, especially after several requests, I would leave no tip at all, as a tip is for services rendered, and if you have asked for service and haven't gotten it, then NO tip is appropriate. $5 would be an exorbitant tip under those circumstances and would constitute a reward for NOT doing his or her job.