How to resolve a purchase block and disabled Apple Account balance due to a security issue?

I have, through the years, seen various posts like yours and to be honest there isn't much you can do. You must have triggered some security feature, but Apple doesn't say much about those. According to various posts, Apple may permanently lock accounts for other reasons (very broadly outlined in section VII-B of Legal - iCloud - Apple ). You, or somebody who has managed to get access to your account, are likely doing something Apple is interpreting as account misuse. You will have to see if your activities could be construed—rightly or wrongly—as meeting any of Apple's conditions in the legal article. You will need to create a new account and stop doing things the way you have been that may have caused the other account to be locked.

In this situation you may be able to still use your equipment with a new account or even no account at all. Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Check the requirements and steps at: Activation Lock support request - https://al-support.apple.com/#/additional-support Apple says, "Proof of ownership documentation is required," but does not detail what currently constitutes proof other than it “must include the product serial number, IMEI or MEID.” Apple may typically require the original receipt* issued by Apple or an Apple Authorized Reseller. If Apple resets the device this will give you access to the device but won't restore access to the account used to lock it. There is nothing that can be done to expedite an Activation Lock request.

*Apple recommends you "Keep your receipt after you buy an Apple device" --> Keep your receipt after you buy an Apple device - Apple Support