DoraS

Newbie here, using the free HMRC software. Managed to mess up my first ever submission, by sending in an FPS for a pay period for before we were even PAYE registered (new company) - the wrong month basically. Any idea how to fix this? I called HMRC and they seemed to think we could submit a correction for the same wrong date but with a zero amount. However, when I tried, the software didn't allow this, showing an error message said a submission for that date has already been made. Any help gratefully recieved.