It's also a good idea to disable Indexes in your httpd.conf Apache config file. This would disable directory listings globally, which is a good idea for production deployments. http://linuxconfig.org/turn-off-directory-browsing-on-apache
I was able to duplicate this functionality as well, here was the output:
posData contains a delimited array of invoice ID's and amounts. In my test, I count 49 characters in posData.
As nelsa mentioned, go back to the page where you got the service information from your screenshot. Below that is an Actions heading with a drop-down selector. Choose "Change Renew Date".