Thanks. So if I want to use 3phase availability here, I need to get them to install a wall charger?
Yes. The only way to get 3-phase into a Model 3 or Y is via a 3-phase wall charger.
Note that 3-phase only gives an extra 50% to the charge rate. It’s not 3x. That’s because the max the 3/Y on-board charger can do is 32A single phase (7.6 kW) or 16A 3-phase (11.5 kW).
For charging at work, I think even 7.6 kW is a lot more than you need. Charging at 15A or 3.6 kW gives about 22 km of range per hour, or 180 km over an 8 hour work day.