Paytm — Paytm delivered wrong product and now not taking back from last one month

Website:

paytm.com

I have ordered "Eureka Forbes Aquaguard Enhance 7 L RO+UV Water Purifier (Black & White)" from paytm site..since the price was less in Paytm, I called them and they confirmed that it's RO+UV model only as mentioned on site. But they delivered RO model... I told them to take this product back on 29-Aug-15 but even after more than one month (today 3-Oct) they didn't take it back yet. every time I call or mail, they will give standard response that we will do reveres pickup in 72 hours but after 72 hours, no update and if i call again.. same response again. Finally after 1 month they told they are not able to do reverse pickup, so telling me to courier but they will give max 200 Rs as courier charges. But it might take 500-1000 Rs to courier Aquaguard, who should bear that charges + 13700 Rs interest for more than one month + inconvenience compensation (as I had to buy minal water from outside from last one month). If somebody from Paytm looking at this - paytm ticket number [protected] (still open)