Telegram Fails to Restore Long-Term User Account

I have been using a Telegram account registered with a Three UK phone number that was originally issued to my friend by a company. I personally used this number and my Telegram account for about two years without any issues, and all of my personal chats, contacts, and important communications are stored there.

On February 28, 2025, I was suddenly logged out of my Telegram account and lost access. Since that date, I have been unable to log back in, recover the account, or delete any of my chats. On February 28, 2026, it will mark one full year since I have been locked out, and I am extremely concerned because there are many personal conversations and sensitive data in the account that I can no longer control.

I understand that the SIM card may be registered as a company line, but I am the long-term user of this phone number on Telegram. I still know the full phone number and can clearly identify my Telegram profile, contacts, groups, and usage history. I am prepared to provide any required verification, including my legal name, identification documents, screenshots, and detailed information about my account activity to prove that this Telegram account belongs to me.

I respectfully request assistance in securely regaining access to my old Telegram account linked to this number, or at least a way to recover or manage the account and its chats after proper identity verification. I also ask for a clear explanation of the steps I must follow and the documents or information needed from me so that this situation, which has lasted nearly a year, can finally be resolved.