You can now return DL games if you are not satisfied: http://t.co/kJ4tloLDB5
— Crin (@crinrict) August 20, 2013
The following screenshot is taken from the guarantee:
As can be seen, this applies only to downloaded games; DLC, such as items bought in the Sims 3 Store, are not applicable for being returned.
To use this guarantee:
1. Click into your order history in your Origin account.
2. Click the “Request a Refund” link by a product you wish a refund on.
3. Fill out the form.
4. You will get a confirmation in 48 hours and a refund in 10 days if you qualify for a refund.
5. If you want to check the status, click into your order history and check My Cases to see if it has been processed.
6. If you have questions, contact EA.