Quote Originally Posted by Arthur Little View Post

... the ECO ought - by rights - to've used his/her commonsense, contacted you about this [easily made] mistake and set you on the proper track - before jumping to conclusions about your application.
IMO ... HAD he/she done that, ... the incorrect form would've automatically been withdrawn and, in due course, superseded by the proper one - without the need for you to stump up another expensive fee.