Bangalore Water Supply & Sewerage Board [Bwssb] — water service converted from domestic to commercial

Address: Bangalore, Karnataka, 560023

We had a water supply from 2008 under domestic charges, however we had additional floor constructed now without a prior notice or information it is converted to partial domestic.. Now when i visited the bwssb they are asking re-apply for coversion and it would cost 10k. Need your assistance to understand the procedure to change from partial domestic to domestic service