I would say the Tauranga Aero Club is a better bet if you're interested in learning at Tauranga. It may also be worth giving BayFlight a try. Air Discovery is okay for Rotorua and Whakatane, though I don't thing they do anything at TRG despite being based there.
Air Discovery are contracted to do all flight training for Tauranga Aero Club. The Aero Club actually has no Instructing staff of their own.