Ask HN: Plain text passwords and big companies

I just received an email from a company:

  - that is a multi-billion dollar company 
  - with whom I spend thousands of dollars a year as a customer

that contained my password in plain text.

As a customer, of this specific company, what should I do?

As a customer, generally in the current era, with ~50 "important" online accounts, how can I protect against incompetent technology practices and avoid headaches? What're best practices for a tech-savvy consumer?

Thanks!