Hi MaryW,
There is no definitive timesale but HMRC will be treating this urgently.
I would recommend speaking to our Debt Management Team in the meantime on 03002003830 so that they can put a note on the file regarding this,
If you do receive any penalties then this can be appealed on the basis that the payment was made on time but the wrong payment reference was used.
Please see below:
Appeal a late payment penalty
Thank you.