Click on this link to read how to update your proof of purchase --> Update your proof of purchase - Apple Support
To update your information contact Apple Support by phone. Tell the advisor that you need help with your Apple Limited Warranty or AppleCare plan expiration date.
Here’s what you need when you call:
- Your AppleCare agreement number
- The device serial number
- Your sales receipt
Note that if you bought them from a third party retailer who is not an official Apple reseller, the warranty started on the date that reseller bought them from Apple, not when you bought them from the reseller (unless the reseller offers their own warranty).