Price differences - Airline tickets.

We booked airline tickets from George Airport to OR Thambo and back on 28 January 2015. The tickets to OR Thambo on SAF Air were R 1 947 for THREE passengers, R349 for luggage included. To fly back to George with SA Express, when we booked, we payed more than R 2 000 PER PERSON! No discount for pensioners, SA Citizens, nothing! Today, 10 April 2015, the price for the SA Express ticket is R1 262 per person. How do you justify these price differences...... It does not make sense to me, please clarify. Thank you