Cannot restore backup on new iphone - fails with incorrect password (but it isn't)

I have a new phone and am trying to move all my information across to the new phone. The backups are encrypted and whenever I try to restore the backup it complains the password is incorrect. I have changed the password made new backups of the old iphone, sync'd the phone backed it up and tried to restore to new phone and it fails.

I have tried an unencrypted backup but whenever I restore it seems to only want to restore from an encrypted backup.

I have tried all sorts of things over the last two days but it is not working so I am now in a position where I have a new phone and I cannot use it.

I have even tried a windows PC rather than a Mac and I still have the same issues.