Radio Troll Question.

First things first if this is the wrong place to post this please let me know.

At my place if work we use the Retevis H-777s, recently someone has been trolling us. Saying slurs and nonsense trying to be funny. We are constantly helping customers and it is mortifyingwhen he chimes in with an insensitive comment. We have just been switching channels to deal with this but it is not working. We have no idea what to do. We are thinking of investing in some nicer radios that are encrypted but they need to be water proof. Not sure if there is a way to file a report on this person. No one here knows anything about radios so any advice is much appreciated. Thanks in advance.

Edit:

Make:Retevis Model: H777s Output power: </= 2w Voltage: 3.7v FCC ID: 2AAR8RETEVISRT24

Additional edit: Thanks so much, everyone. I really appreciate the plethora of information. You all are the best!!