Mistake in locked period

I had made mistake in my payments logging for 22/10/2012.
I deleted the payment and tried to correct mistake. Unfortunately I was able to delete the payment but can not log new payment as that period is locked…
how could I log it to correct the mistake?
There was 6£ entered wrong…thx kl

You can remove the lock date, just by deleting it and saving:

I have done this for you so you should now be able to re-enter the payment.

thank you!
there was a mistake of 6£ for the filed period. do you think I should send that info to HMRC?
thank you

I couldn’t or wouldn’t want to say. I would have a chat with your accountant on that one.