A perfect competitor is a price taker and Transnet is a price maker. The perfect competitor will make normal profit in the short run and the monopoly will make economic profit in the long run. Output of monopoly will cost high but it makes a greater profit to competitors and a perfect competitor produces at less cost and earns a small portion of the profit. Output transnet can decide the quantity of output that is required and price that can be realized.
I hope this helps, Regards.