The most polite way to address this issue is to communicate your feelings and expectations clearly and respectfully. Here are some steps to do so:
Choose the right time and setting: Find a calm and private moment to discuss this matter with the person. Avoid addressing it in front of others or when either of you is feeling particularly upset or stressed.
Use "I" statements: Frame your concerns using "I" statements to avoid sounding accusatory. For example, say, "I feel upset when appointments are canceled last minute or when I'm stood up because it disrupts my schedule."
Express your needs: Share why punctuality and respect for your time are essential to you. Explain how last-minute cancellations or no-shows affect your plans or commitments.
Inquire about their perspective: Give the person an opportunity to explain their behavior. There might be legitimate reasons for their actions, and understanding their viewpoint can help you find a resolution.
Suggest possible solutions: Offer some suggestions to improve the situation, such as asking them to let you know as soon as possible if they need to reschedule or cancel, or finding a more convenient time for both parties.
Set boundaries: Politely but firmly communicate your expectations regarding punctuality and cancellations. Let them know that you value your time and hope they will do the same.
Be open to compromise: Be willing to find a middle ground or alternative arrangements if necessary. Flexibility can lead to a more successful resolution.
Stay calm and composed: Even if you are frustrated, try to keep the conversation calm and respectful. Avoid raising your voice or becoming confrontational.
Reinforce your appreciation: End the conversation on a positive note, expressing your appreciation for their understanding and willingness to improve the situation.
Remember that everyone can occasionally face unexpected situations, and genuine emergencies can happen. However, if the behavior persists without valid reasons, it's essential to address it and set clear expectations for better communication and respect for each other's time.