This is very strange to me because this exchange that you mentioned hold a very high esteem in my heart. I respect them so much as I respect Binance so I would still not want to believe that it is a deliberate action. Everything you have done here is right and I dont see what you need to do again, because you have already contacted the customer support about this situation, and the only thing I would advise is that you keep pressurizing them and also check if they have Instagram account that you can use for further contact.
In as much as we want to help, we might not be able to do so now until probably we are able to actually verify that what you have said is nothing but the truth, so if you can just get us a little proof, then I will be willing to be among people that will retweet it for you.
What kind of screenshots do u need from me to believe me?
Can you sign a message from the address you sent the 100 BTC from? If you can then sign a message and say something like this is the address funds were sent to bittrex. 7 months ago. Then Go and screenshot your deposit address. From bittrex. If you can do both of these I would be happy to help spread awareness to get your funds returned but we need some kind of proof. Post a transaction I.D. of your deposit. Sign a message from the address sent then screenshot the deposit address on bittrex!
Edit you should have no issues doing any of these if it was in fact your wallet that sent these funds. If you post it I will try a few places to help get the issue resolved. If it did in fact happen that is messed up on their part. I like bittrex, With Binance shutting down access to US citizens it is the only exchange I use. But I never deposit over .01 to .02. But I have also never had over .5
BTC let alone 100
BTC...