flipkart - delay in refund

i purchased an ac for my mom in bhagalpur , bihar (i stay in mumbai) on **th june **** , i ordered a * ton voltas split ac from flipkart . i made an advance payment of *****from credit card . i got the product delivered on ** th of june . their technician visited on **th june and installed the ac , but it was a defective piece , the technician took around **** for installation and extra cable . flipkart promised me a replacement and later denied saying time limit for replacement has exceeded. then i asked for a refund , for which they told me to courier the product to their ware house in patna , i requested them for a pick up as it was a difficult task for my mom to courier such a huge appliance , but they said they will process my refund only after the product reaches their patna ware house . they did not provide any contact number and landmark with the address which created a lot of inconvenience in finding the actual place . now the ware house is not accepting the product , saying they only dispatch products and don't receive any , the ac is still with the courier person in patna . the company is not providing any proper solutions . i have also spent **** for stabilizer , *** for labor , **** for courier.