Someone using my email as their Apple ID for purchases in China

Read this document if you think your Apple Account has been compromised. --> If you think your Apple Account has been compromised - Apple Support

For iOS 15 or earlier, if you want to see if anyone else has access to your device or accounts, click here --> Checklist 1: Limit device and account access - Apple Support

For iOS 16 or later see how Safety Check on iPhone works to keep you safe. Safety Check for an iPhone with iOS 16 or later - Apple Support

Use the information in this document to check your Apple ID device list to find where you're signed in --> Check your Apple Account device list to find where you’re signed in - Apple Support

Related materials:

Personal Safety User Guide

Personal Safety User Guide - Apple Support

> open the Table of Contents and review the articles

A document with general information about security and your Apple ID --> Security and your Apple Account - Apple Support

Contact Apple for help with Apple ID account security. This page provides country-specific Apple Support contact information ➞ Contact Apple Support - Apple Support

I am a bit confused by your description. If by "using my email as their Apple ID' you mean they set up an account using your email address, then there are several things that are pretty much impossible about that unless you haven't used that email address in many years. Apple will require a 6 year wait before it will allow a third party email address for re-use as an Apple ID.

If you mean they have access to your account, that is possible and my previous post addressed that. Remember that the people on this support forum are just other customers like you, so we can't speak for Apple. As for account ownership, if you can convince Apple it was truly your account then they will handle it in their way. if you cannot convince them then realize that you can bet pretty much every possible story has been used by social engineering hackers to try to convince Apple to provide access to accounts and Apple is probably very strict in what they will accept as proof. If you cannot regain access then you will have to change any payment methods you have associated with that account and create a new one. Incidentally, having access to the email account is probably not sufficient proof since third party email access security is outside the control of Apple. It could be relatively easy to get somebody's email password. Apple's two factor authentication requires more than one level of proof. The hackers would have to have access to your telephone or other hardware across the ocean.