Hi there! I understand you're having trouble logging into the Sainsbury’s SmartShop app, specifically with your Nectar or Sainsbury’s accounts, and it’s looping you around without letting you in. Let’s see if we can get you back in smoothly.

Could you tell me a bit more about what happens exactly? For example:
- Are you getting any error messages or prompts?
- Is it asking for your password repeatedly, or does it time out?
- Have you recently changed your Nectar or Sainsbury’s account details?
- Have you tried logging in on a different device or browser to see if it behaves the same?

In the meantime, here are some steps that often help with such issues on iPhone iOS 18.7:

1. Clear Cached Data:
Sometimes cached data or cookies cause login loops. Since you’re on an iPhone, you can clear this by uninstalling the SmartShop app.

2. Reinstall the App:
After uninstalling, restart your iPhone and then go to the App Store to download the latest version of the SmartShop app. Using the latest app ensures compatibility and fixes bugs in older versions.

3. Check Your Account Credentials:
Ensure your login details are correct. If you have multiple emails linked to Nectar and Sainsbury’s accounts, it may cause confusion. If you’ve forgotten your password, use the “Forgot Password” option to reset it.

4. Check Account Linking:
Sometimes, the Nectar card and Sainsbury’s account need to be linked or reset if they were linked before. If the app won’t let you in because an account is “already in use” or something similar, that might be why.

Try those steps first, and let me know if any of them help or if you see any new messages or behavior. We can then dive deeper if needed!

If you want, I can guide you through uninstalling and reinstalling the app or resetting your password right now. How would you like to proceed?