Unknown noice on Nissan NV 200 Diesel

We purchased a Nissan NV200 Diesel from Nissan Oudtshoorn dd 12/8/16. We had no problems until after the 1st service which took place 8/8/17 at 13833km. Since then there has been a "intermittent humming" sound from the engine compartment which is now louder. After 2 trips to Oudtshoorn the workshop foreman could not detect the problem. Since then, after numerous visits to DTM George and emails to Nissan's Customer Care Centre, the previous workshop foreman said it was the ABS Pump. The technical person from Nissan SA said that they are not willing to replace the pump. The current workshop foreman says it is the Actuator on the ABS and on another occasion he said it was the Actuator on the Turbo? All emails are on hand. Currently the noise persists but according to Nissan SA the noise is normal. If we should decide to sell the vehicle and the noise is not normal, it will be detrimental to the value of the vehicle. IF ANY BODY HAS THE SAME VEHICLE WITH THE SAME PROBLEM KINDLY DROP US A LINE...... email to: ********** or cell no: ********** 372