http://www.vnbitcoin.org/ Rebate

I don't understand what product you received. I looked up vnbitcoin and all I saw was a cloud mining service with a buy and sell Bitcoin exchange attached.
What is the rebate you are talking about? Do you mean Bitcoin owed to you from hash rate you supposedly purchased?
If you can't get through and have seen no money you were promised for 7 months and have no response to your emails I think it is safe to assume you have been swindled my dear friend.
Of course, I don't even know what you "received" or why you are entitled to a "rebate" so it's hard to say. My guess is
That vnbitcoin are long gone, whoever they are and whatever it is they do.

I hope that clears things up a little for you because now I'm confused

EDIT - I went back and looked at vnbitcoin again and they aren't selling anything actually. It's some website that has BTC and ltc prices some charts and links to download free mining software. It looks sketchy because it doesn't offer anything and you OP are spamming the link to it with some confusing story. Was there things for sale on it 7 months ago? There's sure nothing there now. I would warn against visiting vnbitcoin at all and strongly urge all users to absolutely not download anything that's offered there. I'm on an iPod now and I never use it for anything sensative so I don't care what I browse but I wouldn't touch vnbitcoin with a 50 foot pole on my good computer.

This is a weird one, I think it's click-bait phishing actually.

EDIT 0.2 - Hang on a second! Now I think I've figured this out... they tricked you into using their affiliate link so THEY (vnbitcoin) could get revenue from the affiliate link then kept the rebate that they never had any intention of passing along to you in the first place.
Complain to kncminer, I suppose, you won't get any rebate but vnbitcoin is misleading people and should be banned from advertising for them (and bamboozling you)