I appreciate you for trying the steps presented by my colleagues above, @Ballentine. Let me get you pointed in the right direction to help address this matter.

You can issue a partial refund through QuickBooks Payments without needing your customer's credit card information. Since this feature isn't available in QuickBooks Online.

Here's how:

1. Sign in to your QuickBooks Payments account.
2. Click on the Reverse a Transaction, from the Processing Tools drop-down.
3. Fill out the necessary fields and tap Search.
4. Choose the transaction you want to refund.
5. Type in manually the amount you want to refund in the Amount field, then Submit.
6. A new message will pop up. You'll be asked to select Continue to process a full refund. If you'd like to submit a different amount, select Cancel. You'll then be prompted to enter a different refund amount. Select Continue.
7. A receipt of the transaction will be displayed on the screen. Select E-mail or Print to get a copy of the receipt.

For more information, you can check this link: Void or refund transactions in QuickBooks Payments.

Moreover, you can visit this article for future reference about what fees you could be charged for a refund or voided payment in QuickBooks Payments: Understand fees for refunds or void transactions.

Don't hesitate to comment anytime you have additional questions about processing payments and refunds. We're always here to lend a hand.