Pureit / Hindustan Unilever — Water purifier wasting 50% of water.

Sometimes back I had complained about my purifier Marvelous RO Slim.
It was giving a lot of waste water while the filtration was on.
Someone from the centre came and replaced a few parts.
He also replaced the filter unit.
While he replaced the filter unit, I told him that their is no change in the taste and smell in the filtered water. The technician took me into confidence and said that now with the new designed parts the smell and taste does not change.
I somehow feel that the service centre technicians are playing foul, with replacing repaired or used parts.
Presently when the filter unit is on, it delivers too much of waste water. It also delivers some waste water while the filter unit is off.
Kindly look into the matter.