BMGH wrote:
I have a different password for iCloud but if I use that it gets rejected.
I do not understand this. When visiting iCloud.com, you are presented with this screen:

The iCloud ID is the same as your Apple ID as shown here. So how can you have a different password for iCloud?
BMGH wrote:
I have tried the suggestions in your third bullet point but can't see how to sign out and back in to Wallet and iCloud.
This is my fault, and I apologize. Changes were made with iOS 10.3, and I did not reflect them in my advice above. If you signed out of your Apple ID near the top of Settings, that would suffice.