If you are reading this text, then you probably cannot manage the funds in your btcBank account, since you do not have access to the phone number that you provided when filling out the registration form in btcBank.
If you have lost your phone or your SIM card has failed, remember that all mobile operators allow their users to recover a lost number.
For prepaid subscribers, when recovering a number, 2-3 phone numbers are usually asked for which the last calls or SMS were sent and / or the amount and the date of the last refill.
For contract subscribers, it is usually enough to come to the office with your passport.