We enjoyed nice dives with 2 professional dive mas...

We enjoyed nice dives with 2 professional dive masters. It was well ornagized, the equipment was in good condition and on the boat they offered lunch, fresh fruits, limited coffee and tea. So far it was a good day, with the service which is usual for diving tours in Thailand.
BUT:
Within our last dive, in a deept of approx. 15m, our dive master had no air and needed help from the group. She had panic in her eyes and shocked tbe whole group by showing no air sign.
After the dive she figgured out that one of the dive center team members closed the valve of her air tank before she jumped into the water.

We do not know, was it a joke or a test by her colleagues. But making fun with safety and risking her life for nothing is definitely absolutely unprofessinal. Such a colleague should not continue working for a scuba dive center.
The mood on the boat was killed after that dive.