Havells India — havells water purifier max - acmc

I had purchased havells water purifier in may 2019. At that time upon recommendation of their engineer i bought 2 year comprehensive acmc plan as well, which covers my purifier till 5/5/2022 with change of filters at regular intervals.
As per plan details 5 filters were supposed to be changed in may but no one from havells contacted. I called their customercare on 25th may, 29th may, 11 june and 20th june. Everytime they say that needful will be done in 1-2 days. After the first two calls, i got a call from some of their technician but he had that he can just service the water purifier but cannot change filters. I refused as i have already paid for change of filters at scheduled intervals. Now for the last two times i have called them, i don't even get a callback from them. I either need the filters changed or return me the money i have paid for acmc plan with 1 year interest as well.