To address the high data usage you're experiencing with the Trip.com app and the difficulty in clearing its cache, follow these steps:

1. Check Data Usage Settings:

- Open your iPhone's Settings.
- Scroll down and select Cellular.
- Under the Cellular Data Usage section, locate Trip.com to see how much data it has consumed.
- If the data usage is significant, you can consider disabling Cellular Data for the app. Simply toggle off the switch next to Trip.com. This can help reduce data usage in the future.

2. Clear Cache/Manage App Data:

The Trip.com app doesn't have an explicit option to clear cache directly, but you can try the following methods:

- Delete and Reinstall the App:
- Go to your home screen and find the Trip.com app.
- Long press the app until a context menu appears and select Remove App.
- Confirm by tapping Delete App.
- Go to the App Store, search for Trip.com, and reinstall it. This action usually clears all cached data.

- Background App Refresh:
- In Settings, go to General, then Background App Refresh.
- Toggle off the switch for the Trip.com app. This will prevent the app from using data when not actively in use.

3. Use Wi-Fi Whenever Possible:

- Ensure that you use Wi-Fi networks for app updates, data-heavy tasks, and while searching for travel options. This can prevent excess cellular data consumption.

4. Consider a Data Saving Mode:

- Some apps have a Data Saver feature, but Trip.com may not offer this. Use cellular settings to limit data by navigating back to Settings, then Cellular, and explore Cellular Data Options.

5. Contact Support for Assistance:

If the above methods do not significantly reduce the data usage, consider reaching out to Trip.com customer support. You can find the contact information by logging into your account on their app and navigating to the Customer Support section - learn more.

Implement these steps carefully to manage and reduce the data usage on your device effectively. If you continue facing difficulties, reinstalling the app may provide a solution to reduce overall data consumption.