Hello,
I see that this is frustrating you and seems to be a problem. Well the thing is that if your money is stored on your wallet online it isn't AS safe as having a downloaded wallet. This has happened to many people and it is because of hackers and others finding ways to take your money. Sadly, now that it has been taken and you no longer have it, there isn't anything you can do. The point of mining is to make the server more secure and secure from hackers taking bitcoins from people like they did for you. But now Bitcoin is so much safer due to so many miners. So you won't run into this problem again with bitcoin being as safe as is now. Bitcoin is a really great investment and if you are still up for it you should invest in it.
Thanks,
Matt