Disrespectful staff at boarding gate

The worst experience of my life missing boarding after passing through check in and security checks made my way to slow lounge well in time for my flight. The flights were all delayed and ours not displaying delayed but never once did the info screen go green to indicate "boarding" instead stayed on "go to gate". I then leave lounge to make sure for myself just about 5min before closing time info board still showing "go to gate" arrive at gate only to be laughed at and told flight closed they actually closed the sliding door in my face with other passengers a couple meters ahead in the tunnel would not hear a thing about me boarding since they gave numbers already. I could of of dealt with missing the flight due to my negligence and trusting an info board that now I clearly can't trust in future but the laughing and total disrespect from the gate staff was unessessary.