Our billing department is informed. It may take 2-3 days to process.
May you please let me know what was your purpose but this plugin failed to do that? I may assist you to achieve that or we may add this feature in this plugin so that future user of this plugin can be benefited.

It can be done easily. You can follow https://www.shamimsplugins.com/docs/front-end-pm-pro/getting-started-2/only-admin/ and https://www.shamimsplugins.com/docs/front-end-pm-pro/getting-started-2/role-to-role-block/

Summaries:
1. Set 1 (or more) in Front End PM PRO > Settings > Recipient > Max Recipient
2. Go to Dashboard > Front End PM PRO > Settings > Security > Role to Role Block. Click “Add More” and select “From Role” to “Subscriber”, “To Role” to “Subscriber” and “Block for” to “New Messaage”. Then save changes. Now no subscriber role users will be able to message to another subscriber role users.

Let me know if you have any more question.

1. You can send announcement to any number of users by clicking “Add Announcement” (only admin can do it)
2. You can set any number in max recipient which is more than 0. So set it eg. 100
3. You can set as follows to hide “To” field for subscriber role users. Go to Dashboard > Front End PM PRO > Settings > Security > Role to Role Block. Click “Add More” and select “From Role” to “Subscriber”, “To Role” to “All Roles” and “Block for” to “New Messaage”.

If still not working as you expected, may be i did not understand you properly. You can knock me in skype @shamim_biplob so that i can provide you settings as you want.

Thank you. I have refunded.
As this is just a settings, may be it will be easy to setup as you need. If you have time you can still knock me in skype (or send an email) so that i can try to setup as you need.