 The First Officer was distracted during the turn and did not notice for a while that the aircraft was turning left.When he did notice, he told the captain he was turning the wrong way, and the captain questioned the controller over which way they needed to turn, to which the controller confirmed they were to turn right.A confusing conversation took place over which way to turn, with the controller not having a clear picture of what the flight was doing, due to being unaware that he had left out some critical instructions after his "Merpati 152" mistake and due to the Medan radar system having a refresh time of 12 seconds.