I have been using under-sink Zero-B product for about 6 years, and the main issue is about their service commitments. You have to call them multiple times to attend the issue. However, they promptly remember when the Extended AMC is due for renewal and sometimes call me to schedule the service appointment proactively.
Recently, I raised a complaint on 1st August 2017, and was given complaint number of 8771701220 with a promised commitment of 48hr turnaround time. Since then I had to call their Toll free number 4 times, and still did not receive the service.
I wrote an escalation email today(9th Aug) to their escalation dept. and I got a reply saying that they would resolve my issue. I am not sure if this is the case across India, or just their Hyderabad service center - Kamala Business Solutions.
Zero-B is a good product, but without regular service it is a piece of junk under the sink.
I have decided not to renew the next AMC and go for some other brand.