Yeah i am going to be brief. If you want to check account balance in any nigeria bank account with only account number is 100% possible.
google the bank customer number, copy and call the number. Some one would pick the call tell her that you want to check your account balance, give her the account number and the full name of the account. And boom she will tell you your account balance. You can check any body balance but you must not tell her the account is not yours

OK