You don't have to void the original invoice, Smak1.

I've read your original post. I was wondering why the refund showed as a deposit. A refund shouldn't show as a deposit since this isn't an income transaction. You may want to disregard how it was presented by your third-party merchant service company so you can correctly record the refund in QuickBooks. 

In your case, you'll have to create a credit memo, and choose the give a refund option. 

First, you'll have to delete the deposit transaction. Here's how:

1. Open it.
2. Press Ctrl + D on your keyboard.
3. You'll receive a message, "Are you sure you want to delete this transaction?", then choose OK.

Then, let's edit the credit memo, and choose the give a refund option. This way, it will not double the customer's credit amount. Here's how:

1. Open the credit memo.
2. Click Use credit to give refund.
3. In the Issue a refund window, choose the account you're using for the refund.
4. Click OK, then click Save & Close.

I've attached screenshots as your reference. 

If you have more questions, you can always get back to this thread.