The ideal time and place to resolve a travel-related problem is now. So if you’re experiencing substandard service, say something as soon as possible. Whether you’re staying at a hotel, renting a car or flying, chances are an employee is empowered to help you fix the problem by offering you a different room, a more convenient flight or another vehicle. If that doesn’t work, then a brief, polite e-mail sent to the company after you return is the best course of action.