So angry right now - is there a way to make an official complaint? an ombudsman?

Husband just got an email asking why he hasn't sent the letter which was requested. The same letter that he was told on the phone last Friday that had arrived but wouldn't be looked at for 2-3 weeks. The letter threatens to cancel the application with no refund if letter is not received. One saving grace is an email address has been provided this time, but I am so angry at the way this application has been treated. Is there really no channel of official complaint? Other than approaching an MP?