Oracle password has expired, however I have no way of changing it

If the account is locked, as far as I know, the user can't change it. The Oracle output in your question shows the account is not locked, but expired.

Log in to your database as a user who has privilege to alter other users (for example, SYS) and issue the following command:

ALTER USER tmpdbo IDENTIFIED BY new_password;

You can change the expiration behaviour. There already was a question about that on Stack Overflow:

Make Oracle Password Never Expire

Late to the party here but I just ran into this and at least in my case I am fairly certain it is an oracle bug, possibly with compatibility between client versions. I was getting this error connecting to an 11g database using the 12g sql*plus client while another person was able to successfully log in and change the password using the 11g sql*plus client. They always say things are backwards compatible. They aren't always right...