Taken payment for December till 18th January and no transactions have been loaded since December

Let's fix this issue so you'll be able to update with the latest transactions, exbranch01-iclou.

Before we start, are you getting errors when trying to update your bank? QuickBooks Online downloads the latest available transactions every night. Some banks take a little longer. You'll want to do a manual update to refresh the connection. You can follow the steps below:

1. Go to the Banking menu. Then select  Banking.
2. Click the Update button.

Furthermore, to keep up with the latest transactions, you can download them from your bank and manually upload them in QuickBooks. To do so, you can check out this article so you'll be guided: Manually Upload Transactions Into Quickbooks Online.

Don't hesitate to keep in touch if you need anything else about updating bank transactions. I'll always be right here to help.