Referee Headset, Referee Communication System 4 V4 Plus Referees Talk same time Soccer Football Volleyball Wireless Headsets

The units work great. However i have an ear piece that you cant hear well from. How can i get that one replaced. It doesnt produce much sound

Pairing in general and pairing the 4th headset seems to be problematic?

What is the difference between asin b07p9hst3l and asin b0768ztnsg (same maker; why the prices difference; which is better/worse, etc.); thks?

how do I get replacement headphone earclips? one of mine snapped the first time I put it on, and I'm sure more will snap in the future.