I too had a bad experience with bookadda. They have an attractive site, but that’s about it all.
While doing online shopping, we must stick to those who have a good track record, otherwise it becomes very difficult to pursue matters. Unlike shopping in a store, where you can check and feel the item that you are buying you cannot do so with an online store. So, it is best not to experiment.
The best sites for buying books are https://flipkart.com and https://infibeam.com. I purchase regularly from these sites and till now I am extremely happy with their service. Recently I have purchased two books online, ’Jab se you have loved me...the story of an Airhostess and an IITian, ’ by S.R.Saha and ’Ford County’, by John Grisham. Both are fabulous reads. I would recommend the first one for everybody, not only that it has a fantastic story, but is available for the price of a magazine.