What should I do if my Apple ID is locked?

Your account may have been Locked due to a reason none of us know or even any Apple Support representative. In the Terms of Use for that account and just about every account I have seen, there is a clause that says it can be suspended and may not disclose the reason for that suspension. The representatives you have talked to did the best they could to help, but they are not given any reason either. The solution is to create a new account. You can also see that recommendation here in this support article:

If your Apple Account is locked, not active, or disabled - Apple Support

It makes no difference to us what devices you choose to use and no matter what platform that is, you will see the same comments from frustrated users saying they are never going to purchase another product. It seems to be the go to comment for a reaction and is not one you normally see when asking for help at the same time.

This is a user to user form you are not talking to or getting responses for Apple support. As Mac Jim ID has already informed you, you broke a term condition of Apples terms of service and you’re not gonna be able to use that Apple ID ever again. Apple has given you your only option, create and start using a new Apple ID.