Dear Ahmed, there is a grip on blower, remove it and try to run directly blower from batter, if you see any improvement, then try to clean you blower speed switch by spraying electronic contact cleaner.
if not then open the blower motor, you only need to unscrew three bolts, and check the condition of blower , if there is any deformity then change the blower.
i also wanted to increase blower performance in my Baleno 1.6 Gti which has slightly different dashboard.
from the scarp market, fortunately i found a baleno blower+ motor which was slightly bigger than stock and also in better condition, and there was marked improvement in blower performance and also sound was reduced a bit.
total expense was 1500 at that time(2010/11).