I sent you guys a message yesterday about this fatal error

Hi

I sent you guys a message yesterday about this fatal error message:

Fatal error: Class 'AgmMapModel' not found in /home2/phoneher/public_html/temp/wp-content/plugins/appointments/includes/addons/lib/app_locations.php on line 152

I was told I need to get your Google maps plugin but from what I can see I have to pay another $19 for this plugin. I already have Google maps on our site so I am not looking to spend another $19 when all I need is a appointment booking system. Its really frustrating as the plugin was work beautiful until i was playing around and added google maps and it all went wrong : ( Please could you advise me on what I need to do to solve this problem?? Thanks