I'm sure you have the link already, but here is the contact info including live chat.
Contact - Official Apple Support
Also be aware that it is a common scam to receive these messages and they want you to enter your Apple ID and Password. If they can get this information, not only can they take your data, but also lock you out of your device. Did you give any information from the message when you received it?
If you cannot reset your password and are unable to access any of your information when attempting to sign into iCloud.com, then the last resort is the Account Recovery process.
How to use account recovery when you can’t reset your Apple ID password - Apple Support