Quote

The BTC value at the time of my first two orders was between 901 to 904 USD and was about 981 USD at the time of my third order, but Bitmain took the BTC value for my third order as 917 USD only, I spoke to the Bitmain customer team about this, but they failed to give me a convincing reply and I didn't want to argue further. Anyway, the total value in USD on Invoice copies including shipping is 13226.73 USD.

When you place an order, it'll show you the USD equivalent of BTC. Did you check that at the time of placing your order? BTC pricing is inconsistent, so if you haven't checked pricing at the time of placing your order and maybe checked it before or after that, it's possible that it was 917 and not 981.

Quote

Although I have placed three orders, Bitmain has sent my orders in Six shipments, I asked Bitmain support team about this, they said miners and power supply units are shipped separately.

I haven't ordered from BitMain, but I think most shippers would do the same. They'll ship miner in one package and PSU in other.

Quote

Now, Coming to the customs duties in India, I had no idea about how these customs duties are calculated in India. I tried looking online and on bitcointalk, but couldn't find enough information on this. Somebody told me that I won't be charged more than 10 to 15%, this guy claimed he was charged that much only. But I was prepared for 20% in worst case.

Yea, that's where things get tricky. I've been in a similar situation when I ordered my first SP20E. You've had a bad experience already, but just in case you plan to buy anything else in future, you can make use of this handy tool on BorderLinx website. At least, you won't have to trust some random guy.

Quote

This is my first experience in importing and it has become a nightmare for me. I'm also not happy with Bitmain, I personally think that they should have done something to lessen the burden of taxes on their customers. I still don't understand why they have put the shipping charges on the Invoice, the least they could have done is to not include the shipping charges on the Invoice. I also feel that they should have mentioned the HS codes on the Invoice or somewhere instead of leaving that option to someone who doesn't know anything about these goods. May be I should just blame myself for not digging deeper in to all these before placing the orders.

Instead of blaming BitMain, you should really be blaming the Indian custom, government per say. BitMain isn't imposing taxes on you, the Indian government is. I'll list some of the crappy taxes they impose, for anyone who's interested in know about that.

KRISHI KALYAN CESS -- % minor, but I'm not really sure what that is
SWACHH BHARAT CESS -- % minor, but again I'm not really sure what that is
SERVICE TAX 14%

Besides; there's COUNTER VAILING DUTY, ADDITIONAL CUSTOM DUTY and HANDLING FEE. On top of it, the customs being a government body acts slow as hell. My package was put on hold by them for not less than a month and I've to go back and forth multiple times to get that finally released.

I even had to visit the local sales tax office multiple times to get and fill some forms, which is again wasn't a pleasant experience for me. These guys need to make changes on multiple levels, but I've no idea when that's going to happen (if at all)... Anyways, last word; I think you shouldn't have ordered in bulk when you're not sure about how things work. What's done is done, so let's hope you'll get your machines in one piece and be able to mine to cover your losses.