AO Smith — Cheating with filter replacement

My ao smith x7 water purifier stopped working in march end and i got to know no service de to lockdown. I was waiting till may first week and they started service. One engineer visited on 10th may and changed series of filter some of them are not even used for 2 months and collected 3000 and went. Next day it started warning ro and scpa. Called the engineer multiple times and no response, raised ticket again and escalated to wecare as well daily, no action and not even a call regarding this case even after 6 days. Spent 3000 without even getting 10 litre of water.