Sure, here you go - https://publish.unrealengine.com/v2/faq
This is the excerpt:
**What time frame do I have when requesting a refund? **
You have 10 calendar days from the date of the initial purchase to contact Epic and request a refund. If you have contacted us with a technical issue, we will contact the seller to give them the opportunity to fix it. The seller will be given three days to respond to attempt to resolve the issue. If the issue hasn’t been resolved to your satisfaction, then we will issue the refund