I have lots of expenses that have been marked under telephone that I haven't done, nor are telephone related, taking that expense up to over £1.6k

There are a few ways to rectify the items incorrectly categorised under the wrong category, Adrienne. Let's tackle them one by one so you can decide which works best for you.

First, double-click on the amount to edit the transaction in the report you generated. You can also go to the Expenses page and select the Filter to show entries accordingly. From there, you can change the category.

One of the possible reasons for the auto-categorisation under the Telephone bill is the enabled suggested categorization feature. It auto-categorizes transactions with similar bank details. Let's review your bank setting to verify:

1. Go to the Transactions menu, then Bank transactions.
2. Tap the small Gear icon. 
3. Untick the Enable suggested categorisation checkbox under the Transaction Details.

See these articles to learn more about editing expenses and classifying transactions:

• Enter and manage expenses in QuickBooks Online
• Categorise and match bank transactions in QuickBooks Online

Afterward, scan this guide to detect discrepancies early and ensure your books are accurate: Reconcile an account in QuickBooks Online.

Don't hesitate to ask more questions if ever you need more help handling expenses. I'll make sure everything is sorted out.