I accidentally subscribed to an Advanced plan, but then downgraded to the Quickbooks simple start plan. How will I be credited back the money?

I am not sure they will agree to refund it. You have downgraded the plan intentionally. But you may try to chat Support and ask Billing team to consider it.

I understand that every penny counts when running a business, @weslaughton.

I'm here to help you get back the money you paid for the QuickBooks Online (QBO) Advanced subscription. 

There are two ways to get your credited money. Either your bank will automatically refund the subscription, or QuickBooks will extend the service.

For example: 

You subscribed to QBO Advanced ($180) and Simple Start ($25) without a discount this month. QuickBooks will extend the service to six or seven months (September to April) since you already paid the Advanced subscription. 

I agree with Fiat Lux - ASIA that you can get in touch with our Customer Care Team. They'll be able to further explain your subscription and propose alternative solutions. 
 

Here's how: 

1. Go to the Help menu, then click Contact Us. 
2. Type your concern in the box and tap Let's talk. 
3. Choose either Get a call or Start a chat. 
4. Complete the required data and submit the request.

Make sure to contact them within business hours to ensure a quick response. 

In addition, to know the various features of QuickBooks, visit this article: Comparison of QuickBooks.

Feel free to check out the articles below on how to view payment history and get started in QBO Simple Start:

• Video Tutorial
• View your QuickBooks Online payment history

I'd be happy to help if you have other issues with your subscription. Just leave a comment below. Take care always, @weslaughton.