Caseworkers are getting tons of calls, and 10 minutes can be very hard to find, especially with another person who keeps beeping on the other line, saying "I just turned in my stuff an hour ago. Have you finished my case?"
In the days of the internet, if you can figure out the caseworker's email addy, send caseworker an email with a cc to yourself as proof. Then you have proof for an email. When I really want proof of something, I cc a politician, who usually calls the agency in 24 hours. Use an escalating system of contact.
Emails are really very efficent for the caseworker as well. It gives the caseworker an easy-to-access written acount.
You can always call the supervisor, who gets lots of phone calls, or the regional or state office.