I completed and submitted my application online last 16th November. Neither I or my referees have received any communication regarding my application. I will have the biometrics appointment in one month (early Jan 2020). I will do as you suggest and write a letter to that address explaining the situ...

I am a EU citizen and I received indefinite leave to stay in April 2019. I have recently completed my UK citizenship application by naturalisation (and paid the fee) and somehow I ignored (selective blindness??) the clause about being able to apply only 12 months after being granted indefinite leave...