I am a seller on flipkart, I would like say that there are excutive and admin are very helpful. I am selling my product which are butwhite infuser and few mobile accessories, I found very positive sell and admin support. There are best service for pickup and return, if I found any kind of error about product, I reply admin found instan reply. We are working for you and resolve you problem asap.
Its dashboard is best comparision to other e commerce portal like ebay, amazon and sanpdeal these are very confusing dashboard but this is perfect and easy to process your order after if you have any kind of issue, there are 1000 of customer care. So you can call and find result as u want.
If you want to join as a new seller, you can easily joined with Flipkart. Required few document like address proof bank account and cancle chekc and pan card and find you active flipkart account. I really feel marketplace is complex thing to create and manage. I never felt this while selling on giants market palce like flipkart but while I start another I see this is the best in e commerce site in marketplace.
Thanks