Need advice: how to return the mail.ru mailbox?

Question

Burglary protection

Actually, the essence: they hacked a box on mail.ru.
It was created as a corporate box for communication with Microsoft and other software vendors.
10 years ago (can't remember exactly).
And then I can not send a message - check the password and blah blah blah. I work with mail from my smartphone.
At the same time, incoming messages continue to come to my smartphone email client.
Login through the website mail.ru failed, restore too.
Support response:

Hello.
The mailbox you specified is registered to another user.
Please check that the mailbox name and domain are correct.
Sincerely, Olga Sh. Mail.Ru
user support service

All attempts to agree on something with the support of mail.ru did not lead to anything: the code word is not mine, I stupidly don’t remember in whose name I registered (xs, which of the employees can), I always randomly poked my birthday.
The box continues to work, now rivers of spam mailings are pouring from it to IT suppliers, support has frozen and is silent. He offered to drive up and verify his identity and company documents (and in the correspondence in the box there were all the data on contracts for our company with suppliers) - they kicked back in support with the words "this will not help, we have procedures, you cannot remember the name - so no remember the password".
In general, an amazing result - I was hacked through the fault of the mail.ru code full of holes, and I also remained extreme. I opened a box on Yandex, I'm trying to restore correspondence with counterparties by transferring mail from the phone. Well, I decided to write here, all of a sudden someone knows some solution, faced with frozen mail.ru support.

Answer 1

In general, an amazing result - I was hacked due to the fault of the mail.ru code full of holes and I also remained extreme

Or maybe they hacked through no fault of a leaky code? Typically, such reviews do not finish significant details.
===
and for the future you need to keep the mailbox on your server, but if you are so drawn to free mail, then keep the registration data in order
because the mailer is easy to understand, you can be a fired employee, an ill-wisher ... yes, anyone. you didn't bother to link your box to yourself directly.