sir @pwuser16511011084 please call denso diesel shop 0334 3619493 mr. rafique ask him what he suggest. if the diesel pump is never calibrated since under your ownership he may suggest to service & recalibrate the diesel pump. ask for estimated cost if there is a shop in your city they coordinate with for a solution.
otherwise your mechanic can dismantle the pump dispatch to denso via courier for service & calibration. they send back pump locked sealed for reinstallation. that may resolve your issue for 7+ kms / litre city run. Turn around time is 2 working days after estimate is approved and paid.