It will send you a reminder once but not every 30 min and currently there are no action buttons for the reminder. So it is best to then call a script in the action.
In your actions you will need to call service / and script turn on. So when it times out after 30 min after doing nothing the action happens and then calls your script annoying you until it is done.
The script / blueprint I recommend for this is below. It is nicely done, easy to follow and the developer @samuelthng supports it to date if you have any questions regarding his blueprint. Link is below.
Hope this helps you.
Blacky 