It may be true overwhelmingly that Govt departments recruitment is done out of merit.

However, due consideration must be given to SBP on its recruitment standard on hiring the top-notch people to work for them.

Further, if one has passed NTS test and fulfills minimum 60% recruitment criteria, then higher/lower academic marks do not make one distinguished candidate to be hired. Selection proceeds with the order of merit and provincial, regional and other Govt of Pakistan quota. This is because so no one feels deprived of the top job.

In addition, we all are aware that academic marks can be manipulated, credentials can be forged and lot of other painstaking things can be done to make one a big shot, but it all ends up in vain when you know jack about the job you applied for.

Finally, prepare for interview/GD the way you did for written test. Any less effort will subsequently result in "conspiracy theories" about selection.