TNEB Compalints — frequent voltage fluctuation and power cut

We have frequent voltage fluctuation in Annanagar Y block, 5th street.
Regular fluctuation after 9.30 p.m for the last one week.
Daily I am calling up the respective AE of this area to rectify it.
He promises that problem will not persist from the next day but in vain.
I am scared let my household electrical things may damage. Kindly take some stern action against this negligence.