Hello there, @GarethM,
Let's get you to the right support team who currently handle payroll corrections.
I recommend contacting our QuickBooks Online Payroll Team so they can change the pay period for you. By doing so, you'll be able to re-submit your returns to the HMRC with the correct information. They're open M-F from 8 AM to 8 PM BST.
Here's how to contact them:
- Click the Help button at the right top.
- Click Contact Us.
- Enter a brief discussion of your concern, then click Let's talk.
- Select either Chat or Call us.
Should you need anything else please let me know and I'd be glad to help.