Ao Smith - Item not working fine

Hi,
I have ordered AO SMITH Z* water purifier on *th May and it got delivered on *th May. Installation date was provided as on or before **th May, but it was delayed till **st May, saying reason as Curfew in Bengaluru. I have requested that I have ** months old baby and I can't go outside every day to get water cans and requested to do installation asap. At finally installation was done on **st May i.e., after ** days, really frustrated with service. After installation water was not dispensing properly and it was taken almost * hrs to fill the half tank. I worried and frustrated with the product and service. Really I don't want this kind of product and their service. AO SMITH service engineer is really money minded and he was asking for visiting charges, when I said that I will check with Flipkart and AOSmith then he said no need. After installation when I said it was not working he said that he will come on next day and not on same day. Next day when I called he was not at all responded. I struggled lot and explained everything to filpkart and raised complaint. Still they are saying to wait till **th and not ready for refund. Actually, return date was given as ** th May. But installation done on **st May, how should I get to know whether product is working before installation. It's really big mistake from Flipkart that they should calculate return based installation then only I can tell about performance. Now, when I'm asking for return, they are return time period got over,,, but when I complainted about installation they requested to wait. Really pathetic service.
Please help me to get my money back with compensation for all this struggle that I have faced because of them.