Flight Delay

I recently flew on Mango Airlines flight JE273 from Johannesburg to Durban. The scheduled departure time was 19:55 however the boarding gates for this flight only opened at 19:50 and the plane only took off 20:45. The excuse was a safety check. The plane landed at 22:45 which was 50 minutes later than it should have. This delay is unacceptable because it was almost an hour later. The safety check should have been done earlier than it was (I don't understand why this was only being done once the plane had been boarded by all passengers. The boarding gates for this flight should have also opened much earlier as was scheduled on the flight ticket. (Boarding commenced 25 minutes later). I want to know how I will be compensated for this delay and waste of my time!